简单的图片点击放大

自定义了一个UIImageView的子类

实现思路：

1.为UIImageView添加tap手势

2.在window的keywindow上添加一个透明的遮罩视图

3.tap时，在遮罩视图上创建一个与图片等比例的UIImageView，将图片等比例放大显示在这个imageVIew上，并为遮罩视图添加一个Tap手势用来返回

3.遮罩视图触发Tap时将遮罩视图隐藏

部分代码:

@implementation TapImageView

- (instancetype)init{

    self = [super init];



    self.userInteractionEnabled = YES;

    [self addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(picTapAction:)]];



    return self;

}

- (void)picTapAction:(UIGestureRecognizer *)gr{

    self.hidden = YES;

    _backView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height)];

    _backView.backgroundColor = [UIColor blackColor];

    [_backView addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(backTapAction)]];

    [[UIApplication sharedApplication].delegate.window addSubview:_backView];



    _actionImageView = [[UIImageView alloc] initWithImage:self.image];

    _actionImageView.frame = self.frame;

    [[UIApplication sharedApplication].delegate.window addSubview:_actionImageView];

    [UIView animateWithDuration:.3 animations:^{

        CGFloat fixelW = CGImageGetWidth(_actionImageView.image.CGImage);

        CGFloat fixelH = CGImageGetHeight(_actionImageView.image.CGImage);

        _actionImageView.frame = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, fixelH * [UIScreen mainScreen].bounds.size.width / fixelW);

        _actionImageView.center = _backView.center;

    }];

}

- (void)backTapAction{

    [UIView animateWithDuration:.2 animations:^{

        _actionImageView.frame = self.frame;

        _backView.alpha = .3;

    } completion:^(BOOL finished) {

        [_backView removeFromSuperview];

        [_actionImageView removeFromSuperview];

        self.hidden = NO;

    }];

}

@end