- 原文链接 : Introduction to CocoaPods Tutorial
- 原文作者: Joshua Greene
- 译文出自: 开发技术前线http://www.devtf.cn/
- 译者 : Lollypo
- 校对者: Mr.Simple ,dupengwei
- 状态 : 完成
让多依赖管理更简单
4/14/2014: 完全更新到CocoaPods 0.31和iOS 7 (Marcelo Fabri首发, Joshua Greene更新).
In this tutorial, you’ll learn how to use a popular dependency management tool called CocoaPods.
在这篇教程中, 你将学习到如何使用非常流行的依赖管理工具 -- CocoaPods.
But wait! What is a dependency management tool and why do you need one?
不过，先等一下!到底什么是依赖管理工具？你为什么需要它?
作为一名iOS开发者,你必定会大量使用到他人的代码以及各式各样的库. 想象一下假如你必须从头开始集成每一个库,这将是一件多么蛋疼的事呐!
假如没有依赖管理工具, 你也许仅仅将每个库的代码添加到你的项目中. 但是,这会有几个弊端:
-
Library code is stored within your project, wasting space.
-
There’s no central place where you can see all libraries that are available.
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It can be difficult to find and update a library to a new version, especially if several libraries need to be updated together.
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Downloading and including libraries within your project may tempt you to make changes to the downloaded code and just leave it there (making it harder to update them later).
-
库代码储存在你的项目内,浪费空间.
-
没有一个可以让你看到所有可用的库的中央仓库.
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查找与更新到库的最新版本会变得特别困难尤其是当你需要同时更新多个库时.
-
下载、将库包含到你的项目内可能会让你更改下载的代码或者仅仅让它留在那里(使得后续的更新更加困难).
A dependency management tool can help you overcome these issues. It will fetch library source code, resolve dependencies between libraries, and even create and maintain the right environment to build your project with the minimum of hassles.
依赖管理工具可以帮助你克服这些问题.它将获取源代码库,解决库之间的依赖性,甚至用很小的代价创建和维护适当的环境来构建您的项目.
You’ll get hands on experience using CocoaPods for dependency management in this tutorial. Specifically, you will create an app that uses several open-source libraries to fetch and display information from a popular television and movie information site, trakt.tv.
在本教程中，你将获得使用CocoaPods进行依赖管理的实战经验。具体点说, 你将创建一个应用程序, 它使用一些开源库来从一个受欢迎的电视和电影信息网站trakt.tv获取并显示信息。
CocoaPods will make this project much easier. Read on to see for yourself!
CocoaPods将使这一项目更加简单。 读下去,亲眼看看！
Before you begin: This tutorial assumes you are familiar with Xcode, working with the command line, using AFNetworking, and the JSON format. If you’re completely new to any of these (a basic understanding should be okay), you should refer to the other tutorials on this site first.
在你开始前： 本教程假设你已经熟悉Xcode，命令行的使用,AFNetworking的使用，与JSON格式等。 如果你对这些一点也不了解(有一个基本的了解也是可以的)，你应该先参考本站上的其他教程.
According to its website, CocoaPods is “the best way to manage library dependencies in Objective-C projects.” And in this case, the advertising is true!
按照其官网上所说，CocoaPods是“管理Objective-C项目依赖的最佳方式。”在这种情况下， 这广告是真的！
Instead of downloading code from GitHub and copying it into your project (and thus making future updates difficult), you can let CocoaPods do it for you.
你可以让CocoaPods为你做这些而不是从GitHub上下载代码然后拷贝到项目里去(从而使未来更新困难)。
In this tutorial, you will be building an app that displays upcoming TV episodes using trakt.tv. If you haven’t heard of it, trakt helps you keep track of the shows that you watch. Trakt has several other features, but this is the only one that you will be using in this tutorial.
在本教程中， 你将使用trakt.tv构建一个应用程序显示即将播放的电视节目。如果你还没有听说过它， trakt帮助你跟踪显示你的电视节目。Trakt有这些功能， 但是本篇教程中只会使用到这一功能。
You will retrieve show information from a JSON feed provided by trakt. To simplify downloading, parsing, and showing results, you will use AFNetworking and a few other open-source libraries along the way.
你需要从trakt提供的JSON数据中检索要显示的信息。 在此过程中,为了简化下载, 解析,和显示结果,你需要使用AFNetworking与其他一些开源库。
To get started, you first need to install CocoaPods. CocoaPods runs on Ruby, yet that’s the only dependency it has. Fortunately, all recent versions of Mac OS X (since OS X 10.7 Lion) ship with Ruby already installed. So all you need to do is update RubyGems (just to make sure you have a recent version).
开始， 首先你需要安装CocoaPods。 CocoaPods运行在Ruby上，Ruby是其唯一的依赖。幸运的是， Mac OS X (从 OS X 10.7 Lion) 所有近期的版本都预装了Ruby。 所以你只需要更新RubyGems就可以了(只需确保你使用的是最新版本)。
To do so, open Terminal and type the following command:
为此，打开终端并输入如下命令：
因此,打开终端并输入如下命令:
sudo gem update --system
Enter your password when requested. The Terminal output should look something like this:
当需要时输入你的密码。 终端的输出应该像下面这样：
This update may take a little while, so be patient and give it a few minutes to complete. You can also expect some documentation in the Terminal window about the latest version; you can ignore this for now.
该更新需要花费一点时间。 你需要有耐心并给它几分钟时间来完成，你也可以期待终端窗口会打印关于最新版本的文档信息；目前你可以忽略它。
Next, you need to install CocoaPods. Type this command in Terminal to do so:
下一步，你需要安装CocoaPods。在终端输入这个命令：
sudo gem install cocoapods
You may get this prompt during the install process:
你在安装过程中可能得到这个提示：
rake's executable "rake" conflicts with /usr/bin/rake
Overwrite the executable? [yN]
If so, just enter y to continue. (This warning is raised because the rake gem is updated as part of the install process. You can safely ignore it.)
如果是这样，只需要输入y继续。(这个警告因为更新rake gem是安装过程的一部分。你可以安全地忽略它。)
Lastly, enter this command in Terminal to complete the setup of CocoaPods:
最后， 在终端输入这个命令完成CocoaPods的设置：
pod setup
This process will likely take a while as this command clones the CocoaPods Specs repository into ~/.cocoapods/ on your computer. Great, you’re now setup to use CocoaPods!
这个过程也需要花费一点时间，因为这个命令会克隆CocoaPods Specs库 into ~/.cocoapods/ 到你的计算机上。
太好了, 你现在已经完成了使用CocoaPods的准备工作!
Download the starter project for this tutorial here. This provides a basic UI to get you started – no dependencies have been added yet.
在这里下载本教程的起步项目。 这提供了一个基本的UI让你开始——目前为止没有添加依赖关系。
Open Main.storyboard, and you will see just one view controller:
打开Main.storyboard， 接着你会看到只有一个view controller：
This is the initial view controller, simply called ViewController.
这是初始化的view controller,，简单的称为ViewController。
It has a UIScrollView connected via an IBOutlet to its showsScrollView property and a UIPageControl connected to showsPageControl.
它有一个通过IBOutlet连接到showsScrollView属性上的UIScrollView和一个连接到showsPageControl属性上的UIPageControl 。
It is also set as the delegate for showsScrollView and currently has a single method, pageChanged:, which is connected to the value changed event of showsPageControl.
这被设置为showsScrollView的委托且当前只有一个方法－pageChanged:，这是一个连接到showsPageControl的值发生变化的事件。
Now, close Xcode.
现在， 关闭Xcode。
Yeah, you read that right! It’s time to create your pod file.
是的,你没有看错！是时候创建pod文件了。
打开你的终端并且使用cd命令导航到你的ShowTracker项目目录下:
cd ~/Path/To/Folder/Containing/ShowTracker
下一步输入这个命令:
pod init
This will create a default Podfile for your project. The Podfile is where you define the dependencies your project relies on.
这将会为你的项目创建一个默认的Podfile。这个Podfile就是定义你项目的依赖的地方。
Type this command to open Podfile using Xcode for editing:
输入该命令打开Xcode对Podfile进行编辑：
open -a Xcode Podfile
Note: You shouldn’t use TextEdit to edit the pod file because TextEdit likes to replace standard quotes with more graphically appealing quotes. This can cause CocoaPods to get confused and display errors, so it’s best to just use Xcode or another programming text editor.
注意：你不应该使用文本编辑器来编辑pod文件，因为文本编辑器喜欢替换标准的引号为更生动吸引人的引号。这会使CocoaPods感到困惑并且报错， 所以最好只使用Xcode或另一个编程文本编辑器。
The default Podfile should look like this:
默认的Podfile应该是这样的：
# Uncomment this line to define a global platform for your project
# platform :ios, "6.0"
target "ShowTracker" do
end
Replace # platform :ios, "6.0" with the following:
替换# platform :ios,"6.0"如下：
platform :ios, "7.0"
This tells CocoaPods that your project is targeting iOS 7.
这告诉CocoaPods你的项目是基于iOS 7的。
Many libraries – AFNetworking included – have a minimum iOS version requirement. If you omit this line, CocoaPods assumes a default target version (currently iOS 4.3).
许多库 – 包括AFNetworking都有一个最低的iOS版本要求.如果你忽略了这一行, CocoaPods假定为默认的目标版本(目前是iOS 4.3).
If you’ve only ever programmed in Objective-C, this may look a bit strange to you – that’s because the pod file is actually written in Ruby. You don’t need to know Ruby to use CocoaPods, but you should be aware that even minor text errors will typically cause CocoaPods to throw an error.
如果你只用过Objective-C编程, 这可能会使你感到有点奇怪 – 这是因为pod文件实际上是用Ruby编写的. 使用CocoaPods你不需要知道Ruby, 但你应该意识到,即使是很小的文本错误通常也会导致CocoaPods抛出一个错误.
这将是你用CocoaPods添加第一依赖的最后一步了!复制粘贴下面的文本到你的pod文件中,放在target "ShowTracker" do的后面:
pod 'AFNetworking', '2.2.1'
这会告诉CocoaPods你想要包含AFNetworking 2.2.1版本(本教程编写时的最新版)作为项目的依赖.
This link has more information about the Podfile format and syntax. If you want to do more complicated stuff (like specifying “any version higher than” a specific version of a library), you should definitely check it out.
该链接有更多关于Podfile格式和语法的信息.如果你想做更复杂的东西(比如指定“任何版本高于”一个特定版本的库),你肯定应该看一看。
保存然后关闭pod文件.
You now need to tell CocoaPods to “install” the dependencies for your project. Enter the following command in Terminal to do so (making sure that you’re still in the directory containing the ShowTracker project and Podfile):
现在你需要告诉CocoaPods为你的项目”安装"依赖。在终端输入以下命令(确保你当前所在的目录包含ShowTracker项目和Podfile文件):
pod install
应该会看到类似于下面的输出:
Analyzing dependencies
Downloading dependencies
Installing AFNetworking (2.2.1)
Generating Pods project
Integrating client project
它还可能告诉你这样的事情:
[!] From now on use `ShowTracker.xcworkspace`.
如果你现在输入ls(或者使用Finder浏览你的项目文件夹),您将看到CocoaPods创建了一个Pods文件夹 -- 它储存了所有的依赖项, 还有ShowTracker.xcworkspace.
从现在开始, 如命令行所提示的那样, 你必须打开这个工作区(ShowTracker.xcworkspace) 而不是原本的项目!
关闭Xcode项目(如果你已打开它的话)然后打开ShowTracker.xcworkspace.
在你使用Trakt APIs之前, 你首先需要注册一个免费的账号. 不要担心 – 这会很快而且很简单!
After registering, go to the Settings -> API page to get your API key. Go ahead and leave this page open as you’ll need it soon.
注册之后, 去到Settings -> API页面获取你的API key. 继续操作，并保持这个页面打开,因为你不久之后还会用到它.
To verify that AFNetworking was successfully added, create a new file with the iOS -> Cocoa Touch -> Objective-C 类的模版.
验证AFNetworking是否被成功添加，通过iOS -> Cocoa Touch -> Objective-C类的模版，创建一个新文件。
Name the class TraktAPIClient, and make it a subclass of NSObject.
给这个类命名为TraktAPIClient, 并将其作为NSObject的子类。
确保你将新文件添加到ShowTracker项目而不是Pods项目中 --如果你看看你的项目导航栏, 你将会看到在你的工作区中现在有两个分开的项目.
打开TraktAPIClient.h然后替换原来的代码为如下:
// 1
#import <AFNetworking/AFNetworking.h>
// 2
extern NSString * const kTraktAPIKey;
extern NSString * const kTraktBaseURLString;
// 3
@interface TraktAPIClient : AFHTTPSessionManager
// 4
+ (TraktAPIClient *)sharedClient;
// 5
- (void)getShowsForDate:(NSDate *)date
username:(NSString *)username
numberOfDays:(int)numberOfDays
success:(void(^)(NSURLSessionDataTask *task, id responseObject))success
failure:(void(^)(NSURLSessionDataTask *task, NSError *error))failure;
@end
这是你刚刚做的一些事情:
- 首先导入AFNetworking头文件, 也就是AFNetworking.h. 这其中包括了
AFHTTPSessionManager, 也就是将会作为TraktAPIClient的父类, 和一些其他相关的网络处理类. - 接下来, 声明两个
extern修饰符修饰的字符串常量。 这意味着这些字符串是全局可用的. - 修改
TraktAPIClient去继承AFHTTPSessionManager而不是NSObject, 这在第一步提到了. - 声明
sharedClient方法, 这个方法将会返回一个单例 的TraktAPIClient对象. - 最后, 声明一个辅助方法来使得能很容易地使用trakt API来显示为一个特定的日期,用户名和天数.
You might be wondering, “why did I create TraktAPIClient when AFHTTPSessionManager already handles HTTP requests?”
你可能想知道，既然AFHTTPSessionManager早已能处理HTTP请求,我为什么还要创建TraktAPIClient呢？
TraktAPIClient will make it easier to access the trakt API and make a lot of requests to the same base URL, using the same API key. This also encapsulates all the networking calls and responsibility into a single class.
TraktAPIClient可以使访问trakt API更简单，并且使用同一API密钥将大量的请求转到同一基URL。同时，这也将所有的网络请求和响应封装为一个单独类.
打开TraktAPIClient.m,将其内容替换为如下:
#import "TraktAPIClient.h"
// Set this to your Trakt API Key
NSString * const kTraktAPIKey = @"PASTE YOUR API KEY HERE";
NSString * const kTraktBaseURLString = @"http://api.trakt.tv";
@implementation TraktAPIClient
+ (TraktAPIClient *)sharedClient {
static TraktAPIClient *_sharedClient = nil;
static dispatch_once_t oncePredicate;
dispatch_once(&oncePredicate, ^{
_sharedClient = [[self alloc] initWithBaseURL:[NSURL URLWithString:kTraktBaseURLString]];
});
return _sharedClient;
}
- (instancetype)initWithBaseURL:(NSURL *)url {
self = [super initWithBaseURL:url];
if (!self) {
return nil;
}
self.responseSerializer = [AFJSONResponseSerializer serializer];
self.requestSerializer = [AFJSONRequestSerializer serializer];
return self;
}
- (void)getShowsForDate:(NSDate *)date
username:(NSString *)username
numberOfDays:(int)numberOfDays
success:(void(^)(NSURLSessionDataTask *task, id responseObject))success
failure:(void(^)(NSURLSessionDataTask *task, NSError *error))failure
{
NSDateFormatter* formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"yyyyMMdd";
NSString* dateString = [formatter stringFromDate:date];
NSString* path = [NSString stringWithFormat:@"user/calendar/shows.json/%@/%@/%@/%d",
kTraktAPIKey, username, dateString, numberOfDays];
[self GET:path parameters:nil success:^(NSURLSessionDataTask *task, id responseObject) {
if (success) {
success(task, responseObject);
}
} failure:^(NSURLSessionDataTask *task, NSError *error) {
if (failure) {
failure(task, error);
}
}];
}
@end
这段代码实现你在头文件中做的所有声明:
首先,你声明了字符串常量.确保你替换了PASTE YOUR KEY HERE为你实际的trakt API key.
Next, you implement sharedClient, which uses Grand Central Dispatch (GCD) to create a singleton instance.
接下来, 你实现 sharedClient,它使用 Grand Central Dispatch (GCD)来创建一个单例实例.
You then override initWithBaseURL: and set responseSerializer and requestSerializer to the default JSON serializer for each.
然后重写 initWithBaseURL:然后分别设置 responseSerializer和requestSerializer为默认的JSON serializer 。
最后, 创建帮助方法使用trakt要求的格式来获取电视节目.
现在打开AppDelegate.m然后正确添加如下代码到目前已存在的import语句后:
#import <AFNetworking/AFNetworkActivityIndicatorManager.h>
接着正确添加如下代码的到application:didFinishLaunchingWithOptions:的return语句前:
[AFNetworkActivityIndicatorManager sharedManager].enabled = YES;
This will automatically show the network activity indicator whenever AFNetworking is performing network requests.
每当AFNetworking处理网络请求时，这将会自动显示网络活动的指标。
Next, open ViewController.m and add the following import right after the last one:
接下来, 打开ViewController.m 然后正确添加如下到import语句的最后:
#import "TraktAPIClient.h"
接下来,替换viewDidLoad为如下代码:
- (void)viewDidLoad
{
[super viewDidLoad];
TraktAPIClient *client = [TraktAPIClient sharedClient];
[client getShowsForDate:[NSDate date]
username:@"rwtestuser"
numberOfDays:3
success:^(NSURLSessionDataTask *task, id responseObject) {
NSLog(@"Success -- %@", responseObject);
}
failure:^(NSURLSessionDataTask *task, NSError *error) {
NSLog(@"Failure -- %@", error);
}];
}
这段代码调用刚才创建的帮助方法来显示今天和未来3天的电视节目.
Note: this API queries for tv episodes on a trakt user’s watch list. If you want to use your own username, you will first need to add shows to your watch list from the tv shows category. If you don’t want to do this, use rwtestuser as the username, which already has shows added to it.
注意: 这个API查询用户观看列表上的电视节目. 如果你想使用自己的用户名, 你首先要从TV电视节目分类将电视节目添加到你的观看列表上 . 如果你不想这样做, 使用rwtestuser 作为用户名,该账户预先添加了电视节目.
构建然后运行, 您应该在控制台看到类似如下的输出:
现在你已经在实战中了解了CocoaPods, 现在只剩下一件事了…
Well, actually… you should strive to include as few pods as possible in each of your projects. While CocoaPods makes it easier to update library dependencies, you’re still going to have to update your own code from time to time when you update libraries.
实际上… 你应该努力尽可能减每一个项目中包含的pods。 虽然CocoaPods让你更新依赖库变的更加方便,但每当库更新的时候你仍然要不时的更新自己的代码。
要保证持久运行最好的办法就是控制住你的依赖.
你需要添加两个以上的依赖到项目中.现在你可以在工作区找到Pods文件而不用通过命令行打开.
打开Podfile并将如下两行代码添加到AFNetworking后面:
pod 'SAMCategories', '0.5.2'
pod 'Nimbus/AttributedLabel', '1.2.0'
、保存文件,然后安装依赖(像之前一样在终端输入pod install).
你注意到Nimbus/AttributedLabel pod有什么不同吗?在中间那个斜线叫什么名字?
大的pods通常被分割成几个子模块,依赖一个“核心”模块.在这个案例中,该斜线意味着AttributedLabel是Nimbus的子模块之一.
如果你不熟悉这些库,它们是:
SSToolkit is a handy collection of solutions to common issues faced by iOS developers. In the ShowTracker app, you’ll use it to check if the device has a Retina display.
SSToolkit是iOS开发者面临的常见问题的解决方案集.在ShowTracker应用程序中,您将使用它来检查设备是否支持视网膜显示.
Nimbus, short for NimbusKit, is another collection of useful categories and classes for iOS. You’ll use it mainly for its AttributedLabel component in this app.
Nimbus, NimbusKit的简称, 是另外一个有用的iOS类别与类的集合. 在这个应用程序中你主要使用其AttributedLabel组件。
为了验证一切是否仍然正常, 继续构建应用程序.现在你应该看到了几个警告信息!
“But wait a minute, I haven’t changed any of my project’s code!”, you might be thinking.
“等一下, 我没对代码做什么啊”,你也许会这么想。
当你通过CocoaPods添加依赖时,pod的源文件就被包含在你的项目工作区中.每当你编译你的项目时,它们也被编译.
So, if the pod you’re using has a lot of warnings (or worse, doesn’t compile at all), it may be an indicator that the library is no longer maintained.
因此,如果你使用的pod有许多的警告信息(或者更糟糕,一直无法编译),这意味着该库不再被维护了。
In such a case, you can look for an alternative library on the CocoaPods website by using the search field. You can find detailed information about pods there too, including links to pods’ websites, documentation, and more.
在这种情况下,你可以在CocoaPods网站通过检索字段寻找另外一个替代的库.你能在那里找到关于pod的详细信息,包括pod的网站,文档,以及更多的信息。
然而,在这种情况下,警告主要是由于最近在iOS 7过时的方法(主要是调用“sizeWithFont:”),你可以安全地忽略.
添加下面一行到Podfile的最上面,告诉CocoaPods不再提示pod所有依赖项的警告:
inhibit_all_warnings!
再次运行pod install, 构建你的项目, 你不会看到任何警告了.
太好了, 你现在已经拥有了完成Show Tracker的依赖.所以让我们开始吧!
Open **ViewController.m ** and add the following imports, just after the last one:
打开ViewController.m,并在最后import语句下面添加以下导入语句:
#import <AFNetworking/UIKit+AFNetworking.h>
#import <Nimbus/NIAttributedLabel.h>
#import <SAMCategories/UIScreen+SAMAdditions.h>
Next, add the following properties right after @interface ViewController ():
接下来,添加以下属性到@interface ViewController ()之后:
@property (nonatomic, strong) NSArray *jsonResponse;
@property (nonatomic) BOOL pageControlUsed;
@property (nonatomic) NSInteger previousPage;
这些将用于存储下载的电视节目信息.
在文件的底部创建一个名为loadShow:的方法:
- (void)loadShow:(NSInteger)index
{
// empty for now...
}
This method will be responsible for presenting a page to the user that displays information about a selected TV show episode.
该方法将负责向用户呈现一个页面显示其选择的电视节目的信息。
Now you need to modify viewDidLoad so that it does something useful with the response object instead of simply logging it. First add the following right after [super viewDidLoad];:
现在你需要修改viewDidLoad方法,让它可以通过响应对象做一些有用的事情而不仅仅是记录.首先添加下面一行到[super viewDidLoad];的后面:
self.previousPage = -1;
Then replace the contents of the success block with the following:
然后替换success块的内容为以下语句块:
// Save response object
self.jsonResponse = responseObject;
// Get the number of shows
NSInteger shows = 0;
for (NSDictionary *day in self.jsonResponse)
shows += [day[@"episodes"] count];
// Set up page control
self.showsPageControl.numberOfPages = shows;
self.showsPageControl.currentPage = 0;
// Set up scroll view
self.showsScrollView.contentSize = CGSizeMake(CGRectGetWidth(self.view.bounds) * shows, CGRectGetHeight(self.showsScrollView.frame));
// Load first show
[self loadShow:0];
Now the responseObject JSON is stored, the page control and scroll view are setup, and loadShow: is called to load the first show on success.
现在responseObject的JSON数据被存储了,页面控制和滚动视图被设置,loadShow:被调用且成功加载第一个电视节目.
现在你可以通过以下代码替换loadShow:改变显示信息:
- (void)loadShow:(NSInteger)index
{
// 1 - Find the show for the given index
NSDictionary *show = nil;
NSInteger shows = 0;
for (NSDictionary *day in self.jsonResponse) {
NSInteger count = [day[@"episodes"] count];
// 2 - Did you find the right show?
if (index < shows + count) {
show = day[@"episodes"][index - shows];
break;
}
// 3 - Increment the shows counter
shows += count;
}
// 4 - Load the show information
NSDictionary *showDict = show[@"show"];
// 5 - Display the show title
UILabel *titleLabel = [[UILabel alloc] initWithFrame:CGRectMake(index * CGRectGetWidth(self.showsScrollView.bounds) + 20, 40, CGRectGetWidth(self.showsScrollView.bounds) - 40, 40)];
titleLabel.text = showDict[@"title"];
titleLabel.backgroundColor = [UIColor clearColor];
titleLabel.textColor = [UIColor whiteColor];
titleLabel.font = [UIFont boldSystemFontOfSize:18];
titleLabel.textAlignment = NSTextAlignmentCenter;
// 6 - Add to scroll view
[self.showsScrollView addSubview:titleLabel];
}
构建运行,然后你会看到是这样的:
酷,今晚行尸走肉将会更新,不过是哪一季呢?
添加以下代码到**loadShow:**中放在section #6的后面:
// 5.1 - Create formatted airing date
static NSDateFormatter *formatter = nil;
if (!formatter) {
formatter = [[NSDateFormatter alloc] init];
formatter.dateStyle = NSDateFormatterLongStyle;
formatter.timeStyle = NSDateFormatterShortStyle;
formatter.timeZone = [NSTimeZone timeZoneWithAbbreviation:@"PST"];
}
NSDictionary *episodeDict = show[@"episode"];
NSTimeInterval showAired = [episodeDict[@"first_aired_localized"] doubleValue];
NSString *showDate = [formatter stringFromDate:[NSDate dateWithTimeIntervalSince1970: showAired]];
// 5.2 - Create label to display episode info
UILabel *episodeLabel = [[UILabel alloc] initWithFrame:CGRectMake(index * CGRectGetWidth(self.showsScrollView.bounds),
360, CGRectGetWidth(self.showsScrollView.bounds), 40)];
NSString* episode = [NSString stringWithFormat:@"%02dx%02d - \"%@\"",
[[episodeDict valueForKey:@"season"] intValue],
[[episodeDict valueForKey:@"number"] intValue],
[episodeDict objectForKey:@"title"]];
episodeLabel.text = [NSString stringWithFormat:@"%@\n%@", episode, showDate];
episodeLabel.numberOfLines = 0;
episodeLabel.textAlignment = NSTextAlignmentCenter;
episodeLabel.textColor = [UIColor whiteColor];
episodeLabel.backgroundColor = [UIColor clearColor];
CGSize size = [episodeLabel sizeThatFits:CGSizeMake(CGRectGetWidth(self.view.frame),
CGRectGetHeight(self.view.frame) - CGRectGetMinY(episodeLabel.frame))];
CGRect frame = episodeLabel.frame;
frame.size.width = self.view.frame.size.width;
frame.size.height = size.height;
episodeLabel.frame = frame;
[self.showsScrollView addSubview:episodeLabel];
This creates a label containing info about the episode, including season, episode number, title and a human-readable date and time it’s going to be aired.
这将创建一个包含关于这一剧集的信息标签,包括季数,集数,标题和一个人类可读的播出日期和时间.
构建运行,你现在可以看到,《行尸走肉》已经在播第4季了!
是不是觉得好像有什么在呼唤你将屏幕的中心巨大的空白的填满?如果放一张图片会怎样?
还是在**loadShow:**方法中, 添加如下代码到 section #6后面:
// 5.3 - Get image
NSString *posterUrl = showDict[@"images"][@"poster"];
if ([[UIScreen mainScreen] sam_isRetina]) {
posterUrl = [posterUrl stringByReplacingOccurrencesOfString:@".jpg" withString:@"-300.jpg"];
} else {
posterUrl = [posterUrl stringByReplacingOccurrencesOfString:@".jpg" withString:@"-138.jpg"];
}
// 5.4 - Display image using image view
UIImageView *posterImage = [[UIImageView alloc] init];
posterImage.frame = CGRectMake(index * CGRectGetWidth(self.showsScrollView.bounds) + 90, 105, 150, 225);
[self.showsScrollView addSubview:posterImage];
// 5.5 - Asynchronously load the image
[posterImage setImageWithURL:[NSURL URLWithString:posterUrl] placeholderImage:[UIImage imageNamed:@"placeholder.png"]];
This code first determines the image to download based on whether the device has a retina display (since there is no need to download a larger image on a non-retina device). Note that isRetinaDisplay is a helper method included from SSToolkit.
这段代码首先根据设备是否支持视网膜显示决定是否要下载图片(因为不需要在非视网膜设备上下载大图)。注意isRetinaDisplay｀是SSToolkit中的一个帮助方法.
之后,一个UIImageView被创建然后添加到滚动视图中.
Finally, the image is downloaded and set on the image view, using the convenience method provided by AFNetworking. This method also sets a placeholder image that is displayed until the download is finished.
最后,使用AFNetworking提供的便利方法下载图像并设置到图像视图上.该方法还设置一个占位符显示图像,直到下载完成。
构建运行,你将看到该电视节目的美丽的海报.
太棒了!你现在有显示第一个节目的信息但是其他的呢?
您首先需要通过showsPageControl在分页视图上显示其他电视节目信息.
替换pageChanged:方法为如下代码:
- (IBAction)pageChanged:(id)sender
{
// Set flag
self.pageControlUsed = YES;
// Get previous page number
NSInteger page = self.showsPageControl.currentPage;
self.previousPage = page;
// Call loadShow for the new page
[self loadShow:page];
// Scroll scroll view to new page
CGRect frame = self.showsScrollView.frame;
frame.origin.x = frame.size.width * page;
frame.origin.y = 0;
[UIView animateWithDuration:.5 animations:^{
[self.showsScrollView scrollRectToVisible:frame animated:NO];
} completion:^(BOOL finished) {
self.pageControlUsed = NO;
}];
}
Here pageControlUsed is set to YES, indicating that the new page will be shown because the user selected it with the page control and not by scrolling the scroll view. (You’ll need this later when you handle scrolling using the scroll view.)
这里pageControlUsed被设为 YES,表明新页面被显示是因为用户通过页面控制选择它而不是通过滑动滚动视图。(稍后你需要使用滚动视图处理滚动事件).
Then, the new page is loaded and its frame calculated. Finally, the new page is displayed on the screen.
然后,新页面被加载以及其frame的计算。最后,新页面显示在屏幕上。
Build and run. You can now navigate through pages using the page control. Simply tap on the circles in the page control and the screen will navigate to the next or previous page. Cool, isn’t it?
构建运行,您现在可以使用页面控制浏览页面。简单地点击页面控制中的圆圈，屏幕将导航到下一个或上一个页面。很酷,不是吗?
但是,有些东西不见了…当页面滚动的时候发生了什么?如果你这样尝试过,你会发现你得到了空白页, 除非你已经使用视图控制滚动到页面.让我们修复它吧.
Paste the following UIScrollViewDelegate methods at the end of the file:
将下面的UIScrollViewDelegate方法粘贴到文件的末尾:
- (void)scrollViewDidScroll:(UIScrollView *)sender
{
// Was the scrolling initiated via page control?
if (self.pageControlUsed)
return;
// Figure out page to scroll to
CGFloat pageWidth = sender.frame.size.width;
NSInteger page = floor((sender.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
// Do not do anything if we're trying to go beyond the available page range
if (page == self.previousPage || page < 0 || page >= self.showsPageControl.numberOfPages)
return;
self.previousPage = page;
// Set the page control page display
self.showsPageControl.currentPage = page;
// Load the page
[self loadShow:page];
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
self.pageControlUsed = NO;
}
Note the use of self.pageControlUsed. That’s because when the scroll view offset is changed in pageChanged (when you change the page using the page control), scrollViewDidScroll: is called, but if you handled the scrolling at that point, you’d be loading the same page twice. So you need to detect when scrolling is initiated via the page control and do nothing.
注意self.pageControlUsed的作用。那是因为当滚动视图位移在pageChanged中发生改变时(当你使用页面控制更改页面)，scrollViewDidScroll:被调用，但如果你那时处理滚动,你会两次加载同一个页面。所以你需要通过页面控制检测scrolling何时启动，且什么也不做。
Build and run, and you can now navigate through the shows by scrolling too!
构建并运行,你现在也可以通过滚动浏览电视节目!
But what if the user wants to know more about the show? Trakt has a page for every show registered, and its URL is in the information the app has already received.
但是,如果用户想要知道更多关于这个节目的信息呢？对于每个已注册的节目，Trakt有一个页面对其进行管理，并且app已经接收到了每个节目对于的URL信息。
You can use NIAttributedLabel to present it.
你可以使用NIAttributedLabel 进行表示。
在ViewController.m的顶端,替换@interface ViewController ()为如下:
@interface ViewController () <NIAttributedLabelDelegate>
This declares that ViewController conforms to the NIAttributedLabelDelegate protocol.
这声明ViewController遵从NIAttributedLabelDelegate协议。
Now add the following NIAttributedLabelDelegate method at the bottom of ViewController.m:
现在添加下面的NIAttributedLabelDelegate方法到ViewController.m的底部:
- (void)attributedLabel:(NIAttributedLabel *)attributedLabel didSelectTextCheckingResult:(NSTextCheckingResult *)result atPoint:(CGPoint)point
{
[[UIApplication sharedApplication] openURL:result.URL];
}
This delegate method is called when a link is selected. It simply requests UIApplication to open the URL, which will result in Safari being launched to open it.
当某个链接被点击时这个委托方法就会被调用。它只是请求UIApplication打开URL，这将启动Safari以打开它。
But how can one add a link to the label displayed in the app? Simple, just change the implementation of loadShow: in section #5 so that the label displaying the show title is an NIAttributedLabel instead of a UILabel.
但如何为app中显示的标签添加链接？很简单,就是改变#5部分的loadShow:的实现,显示节目标题的标签是一个NIAttributedLabel而不是UILabel。
Replace the // 5 - Display the show title section with the following:
替换// 5 - Display the show title部分为如下代码:
// 5 - Display the show title
NIAttributedLabel *titleLabel = [[NIAttributedLabel alloc] initWithFrame:CGRectMake(index * CGRectGetWidth(self.showsScrollView.bounds), 40, CGRectGetWidth(self.showsScrollView.bounds), 40)];
titleLabel.text = showDict[@"title"];
titleLabel.backgroundColor = [UIColor clearColor];
titleLabel.linkColor = [UIColor redColor];
titleLabel.font = [UIFont systemFontOfSize:18];
titleLabel.textAlignment = NSTextAlignmentCenter;
[titleLabel addLink: [NSURL URLWithString:showDict[@"url"]] range:NSMakeRange(0, titleLabel.text.length)];
titleLabel.delegate = self;
The main difference is the existence of linkColor, and addLink:. It’s also important to set the label’s delegate to self, which represents the current instance of the ViewController.
主要的区别是 linkColor与addLink:的存在。这与设置委托标签为self同样重要,表示ViewController当前实例.
Build and run, and you will see the show title in red. If you click it, Safari will open with the show page from trakt!
构建并运行,你将看到标题显示为红色。如果你点击它,Safari浏览器将打开来自trakt的节目页面。
你可以从这里下载完成的项目.
Now that you know the basics of using CocoaPods, you can read through the CocoaPods Guides to learn the finer details of using CocoaPods, including how to create your own pod spec and submit it to the official repository.
现在你对于CocoaPods的使用有了基本的了解, 你可以通过阅读CocoaPods Guides学习CocoaPods更细节的使用方法，包括如何创建自己的pod说明书与如何提交到官方仓库。
To check if CocoaPods already supports a specific library, you can search the CocoaPods website.
要检查CocoaPods是否已经支持某个库,你可以搜索CocoaPods网站。
这里有一些我认为最有用的库:
- AFNetworking: 网络连接和响应处理.
- CorePlot: 绘图框架.
- MagicalRecord: 超级棒, 很方便的获取Core Data 1!!!11!!!!1!
- MBProgressHUD: 一个活动的指示器,可添加到你的View上
- Nimbus: 保持iOS框架与文档一致.
You should also check out the trakt API. It’s well-documented, and you can do a lot of things with it.
你也应该看看trakt API文档。文档齐全,而且你也可以用它做很多事情.
Regarding the sample application, there are many improvements you could make, such as:
对于这个案例程序, 有许多地方你可以改进, 例如:
-
What happens if there isn’t a TV show for the given date range?
-
What if there are a lot of shows? None of the pages that are loaded are thrown away, and this can quickly consume a lot of memory!
-
There’s more information to be displayed – like a synopsis, the channel airing the show, etc.
-
如果给定日期范围内没有电视节目会怎样？
-
如果有很多节目怎么办？所有的页面都被加载，然后没有页面被丢弃, 这很快就会消耗大量的内存！
-
有更多的信息需要被展现出来 – 例如简介,显示频道播出的节目等等.
我希望你喜欢这个教程,而且我期望在论坛上阅读你的评论.
想知道其他有用的库吗？告诉我们！你创建过一个pod说明书吗？也告诉我我们让我们知道!