January 2020
Intermediate to advanced
356 pages
6h 4m
Chinese
Content preview from Swift游戏开发经典实例
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此外，
UIViewController
需要负责对来自子视图中的事件进行处理，对这些控件
进行操作并改变它们的状态。
这一切需要通过
Outlet
和
Action
进行
。一个
Outlet
是
UIViewController
的一个
属性，它代表了一个视图或者控件。当
viewDidLoad
被调用后，每个
Outlet
属性都
会和视图上的一个对象关联起来。我们可以像访问一般的属性一样访问它们。
要定义一个
Outlet
，我们需要用关键字
IBOutlet
来声明一个属性，例如：
@IBOutlet weak var textField: UITextField!
Action
是一个方法，当用户与屏幕上的控件进行交互时这个方法会被调用。例如，
当我们想知道何时一个按钮被用户按下时，我们可以创建一个
Action
方法，然后
将这个方法和按钮关联起来。我们可以为控件的各种事件创建
Action
，例如文本框
的文本内容发生改变，或者滑块位置被移动等。
Action
方法在类的
@interface
中定义，例如：
@IBAction func buttonPressed(_ sender: AnyObject) {
注意，
IBAction
并不是真正的返回类型，
IBAction
实际上是
void
的别名。
Xcode
只是使用
IBAction
关键字来表示一个方法可以和
IB
中的某个视图关联在一起。
接下来，这个
Action
声明了一个参数：一个
sender
对象。这个对象代表了调用
Action
方法的对象：被触摸的按钮对象，或者正在接受输入的文本框等。 ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.