UIButton事件的边界问题

[TOC]

问题描述

最近在做语音输入按钮时，利用UIButton来处理。当手指拖拽出button边界时，UIControlEventTouchDragExit并未立即触发，继续托拽出距离button边界大约70像素时才触发。

代码实现

- (void)setVoiceBtnEvent {
    [_voiceBtn addTarget:self action:@selector(btnTouchUp:withEvent:) forControlEvents:UIControlEventTouchUpInside];
    [_voiceBtn addTarget:self action:@selector(btnTouchUp:withEvent:) forControlEvents:UIControlEventTouchUpOutside];
    [_voiceBtn addTarget:self action:@selector(btnDragged:withEvent:) forControlEvents:UIControlEventTouchDragInside];
    [_voiceBtn addTarget:self action:@selector(btnDragged:withEvent:) forControlEvents:UIControlEventTouchDragOutside];
}
// touch up
- (void)btnTouchUp:(UIButton *)sender withEvent:(UIEvent *)event {
    UITouch *touch = [[event allTouches] anyObject];
    CGFloat boundsExtension = 10.0f;// 触发边界暂时设置为10
    CGRect outerBounds = CGRectInset(sender.bounds, -1 * boundsExtension, -1 * boundsExtension);
    BOOL touchOutside = !CGRectContainsPoint(outerBounds, [touch locationInView:sender]);
    if (touchOutside) {
        // UIControlEventTouchUpOutside

    } else {
        // UIControlEventTouchUpInside

    }
}
// drag
- (void)btnDragged:(UIButton *)sender withEvent:(UIEvent *)event {
    UITouch *touch = [[event allTouches] anyObject];
    CGFloat boundsExtension = 10.0f;// 触发边界暂时设置为10
    CGRect outerBounds = CGRectInset(sender.bounds, -1 * boundsExtension, -1 * boundsExtension);
    BOOL touchOutside = !CGRectContainsPoint(outerBounds, [touch locationInView:sender]);
    if (touchOutside) {
        BOOL previewTouchInside = CGRectContainsPoint(outerBounds, [touch previousLocationInView:sender]);
        if (previewTouchInside) {
            // UIControlEventTouchDragExit

        } else {
            // UIControlEventTouchDragOutside
        
        }
    } else {
        BOOL previewTouchOutside = !CGRectContainsPoint(outerBounds, [touch previousLocationInView:sender]);
        if (previewTouchOutside) {
            // UIControlEventTouchDragEnter

        } else {
            // UIControlEventTouchDragInside

        }
    }
}