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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88
｜
第
3
章
移动
手指从一个地方移动到另一个地方（在一个触摸过程中，移动方法会被调用多
次）。
结束
手指从屏幕上离开。
取消
触摸由于某种原因被中断，比如被某个手势识别器拦截（本章
3.2
节）。
当手指一放到屏幕上，
iOS
首先判断该由哪个视图负责处理这个触摸。首先判断屏
幕被触摸的位置，以及该位置所处的视图；然后判断这个视图或者其子视图是否能
处理这个触摸。也就是检查这个视图（或者其子视图）是否实现了
touchesBegan
、
touchesMoved
、
touchesEnded
或者
touchesCancelled
方法。
一旦判定触摸属于某个视图，则每当触摸状态发生改变时，这些方法就会被调用（比
如两指同时在屏幕上滑动），每个方法都有一个包含每个触摸及其状态的
Set
集合
参数。
3.2
处理轻触手势
问题
当用户轻触视图时，我们如何检测到这个手势？
解决方案
轻触是指用户以单指触碰屏幕，然后在原地抬起手指。可以使用一个手势识别器
UIGestureRecognizer
（其实是它的子类
UITapGestureRecognizer
）来识别轻触手势：
override func viewDidLoad() {
super.viewDidLoad()
let tap = UITapGestureRecognizer(target: self,
action: #selector(ViewController.tap(tapRecognizer:)))
输入
｜
89
//
这里，可以将手势识别器添加到视图控制器 ...
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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.