iOS捕捉截屏事件并展示截图

摩拜单车、微信的截屏就做的比较人性化。
现在很多APP开始支持用户截屏后，主动获取截图并弹出分享视图，这样用户就不用去相册去找了，感觉体验不错，今天就分享一下 截屏开发的心得，希望能帮助iOS的朋友。

iOS7之后，苹果开放出一个通知：UIApplicationUserDidTakeScreenshotNotification，截屏时系统就会发出这个通知，需要你注册这个通知，就能捕捉到截屏图片。

下面的代码，实现的是用户截屏后，捕获到截屏图片，展示出来：

//注册截屏通知

 [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(getScreenShot:)
                                                 name:UIApplicationUserDidTakeScreenshotNotification object:nil];

截屏后捕捉到事件：

- (void)getScreenshot:(NSNotification *)notification{
    NSLog(@"捕捉截屏事件");

    //获取截屏图片
    UIImage *image = [UIImage imageWithData:[self imageDataScreenShot]];

    //显示图片
    UIImageView *imgV = [[UIImageView alloc]initWithImage:image];
    imgV.frame = [UIScreen mainScreen].bounds;

    UIView *backView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT)];
    backView.backgroundColor = [[UIColor grayColor] colorWithAlphaComponent:0.8];

    UIButton *shareBtn = [UIButton buttonWithType:UIButtonTypeSystem];
    shareBtn.titleLabel.font = [UIFont systemFontOfSize:17.0];
    [shareBtn setTintColor:[UIColor whiteColor]];
    shareBtn.frame = CGRectMake(SCREEN_WIDTH/5,SCREEN_HEIGHT ,SCREEN_WIDTH*3/5,50);
    [shareBtn.layer setMasksToBounds:YES];
    [shareBtn.layer setBorderWidth:1];
    shareBtn.layer.cornerRadius = 6;
    [shareBtn setTitle:@"分享给好友" forState:UIControlStateNormal];
    shareBtn.backgroundColor = [SouFunIMUtilityHelper colorWithHexString:@"#B22222"];
    [shareBtn addTarget:self action:@selector(shareBtn:) forControlEvents:UIControlEventTouchUpInside];

    [backView addSubview:imgV];
    [backView addSubview:shareBtn];

    UIWindow *window = [UIApplication sharedApplication].keyWindow;
    [window addSubview:backView];

    [UIView animateWithDuration:1.0 animations:^{
        imgV.transform = CGAffineTransformMakeScale(0.8, 0.8);
        shareBtn.transform = CGAffineTransformMakeTranslation(0, -50);
    }];
    //3秒后消失
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [backView removeFromSuperview];
    });
}

获取截屏图片data：

- (NSData *)imageDataScreenShot
{
    CGSize imageSize = CGSizeZero;
    imageSize = [UIScreen mainScreen].bounds.size;

    UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
    CGContextRef context = UIGraphicsGetCurrentContext();
    for (UIWindow *window in [[UIApplication sharedApplication] windows])
    {
        CGContextSaveGState(context);
        CGContextTranslateCTM(context, window.center.x, window.center.y);
        CGContextConcatCTM(context, window.transform);
        CGContextTranslateCTM(context, -window.bounds.size.width * window.layer.anchorPoint.x, -window.bounds.size.height * window.layer.anchorPoint.y);
                if ([window respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)])
        {
            [window drawViewHierarchyInRect:window.bounds afterScreenUpdates:YES];
        }
        else
        {
            [window.layer renderInContext:context];
        }
        CGContextRestoreGState(context);
    }

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return UIImagePNGRepresentation(image);
}

按钮点击事件：

-(void)shareBtn:(UIButton *)sender{

/*
    分享代码 
*/
}

以上就是截屏后的事例代码，最后附上效果图：