有個(gè)需求，就是需要超出視圖部分上面的按鈕能夠響應(yīng)點(diǎn)擊事件，大概如圖所示：

Paste_Image.png

說一下大概情況，就是有一個(gè)容器v1(紅色)，上面又一個(gè)元素v2（綠色）。v2的上面又有一個(gè)元素v3（藍(lán)色）,v3有一部分超出了v2的邊界，并且超出部分上面還存在一個(gè)按鈕（右下角）?，F(xiàn)在要求點(diǎn)擊右下角按鈕，能夠讓按鈕響應(yīng)事件。

繪制界面的代碼如下：

 do {
        View1 *v = [View1 new];
        self.v1 = v;
        v.backgroundColor = [UIColor redColor];
        [self.view addSubview:v];
        [v makeConstraints:^(MASConstraintMaker *make) {
            make.width.equalTo(300);
            make.height.equalTo(300);
            make.top.equalTo(self.view);
            make.centerX.equalTo(self.view);
        }];
    } while (0);
    do {
        View2 *v = [View2 new];
        self.v2 = v;
        v.backgroundColor = [UIColor greenColor];
        [_v1 addSubview:v];
        [v makeConstraints:^(MASConstraintMaker *make) {
            make.width.equalTo(100);
            make.height.equalTo(100);
            make.top.equalTo(self.view);
            make.centerX.equalTo(self.view);
        }];
    } while (0);
    do {
        View3 *v = [View3 new];
        self.v3 = v;
        v.backgroundColor = [UIColor blueColor];
        [_v2 addSubview:v];
        [v makeConstraints:^(MASConstraintMaker *make) {
            make.width.equalTo(100);
            make.height.equalTo(100);
            make.centerX.equalTo(self.view).offset(50);
            make.bottom.equalTo(_v2).offset(20);
        }];
    } while (0);
    UIButton  *btn = [UIButton new];
    [btn setBackgroundImage:[WJCommonUtils imageFromColor:RGBCOLOR(200, 100, 100)] forState:UIControlStateNormal];
     [btn setBackgroundImage:[WJCommonUtils imageFromColor:RGBCOLOR(100, 100, 200)] forState:UIControlStateHighlighted];
    [_v3 addSubview:btn];
    [btn makeConstraints:^(MASConstraintMaker *make) {
        make.width.height.equalTo(20);
        make.right.equalTo(_v3);
        make.bottom.equalTo(_v3);
    }];

我們知道了iOS下的事件傳遞機(jī)制，因此可以通過重寫view的hitTest方法來控制事件傳遞。因?yàn)榭梢赃@樣改：

重寫v1的hittest方法:

#import "View1.h"
#import "choose.h"

@implementation View1

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
    NSLog(@"View1 hitTest start ");
    UIView *item = [super hitTest:point withEvent:event];
    if (item == self) {
        NSArray *array = [choose choose:@"View3"];
        if (array.count>0) {
            UIView *v = (UIView *)array.lastObject;
            CGPoint p = [self convertPoint:point toView: v];
            item = [v hitTest:p withEvent:event];
        }
    }
    NSLog(@"View1 hitTest - %@",item);
    return item;
}

@end

搞定!