iOS hitTest方法&pointInside方法

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<h4>hitTest方法</h4>

<ul>
<li>当事件传递给控件的时候，就会调用控件的这个方法，去寻找最合适的view</li>
<li>point：当前的触摸点，point这个点的坐标系就是方法调用者</li>
</ul>

 

<pre><code class=""language-objc"" lang=""objc"">- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event;
</code></pre>

<h4>pointInside方法</h4>

<ul>
<li>作用：判断当前这个点在不在方法调用者（控件）上</li>
</ul>

 

<pre><code class=""language-objc"" lang=""objc"">- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event;
</code></pre>

<h4>hitTest:withEvent:的实现原理</h4>

 

<pre><code class=""language-objc"" lang=""objc"">- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{

// 1.判断当前控件能否接收事件
if (self.userInteractionEnabled == NO || self.hidden == YES || self.alpha <= 0.01) return nil;

// 2. 判断点在不在当前控件
if ([self pointInside:point withEvent:event] == NO) return nil;

// 3.从后往前遍历自己的子控件
NSInteger count = self.subviews.count;

for (NSInteger i = count – 1; i >= 0; i–) {
UIView *childView = self.subviews[i];

// 把当前控件上的坐标系转换成子控件上的坐标系
CGPoint childP = [self convertPoint:point toView:childView];

UIView *fitView = [childView hitTest:childP withEvent:event];

if (fitView) { // 寻找到最合适的view
return fitView;
}
}
// 循环结束,表示没有比自己更合适的view
return self;
}
</code></pre>

<pre><code> "“`

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