产品需求：在APP内部，当监听到用户有截屏行为的时候，提示用户进行分享APP页面，达到引流的效果；

废话不多说，直接上效果图：

share.jpg

具体做法：

• 1.首先在 AppDelegate.m文件的方法didFinishLaunchingWithOptions里面设置监听截屏行为

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
       [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(userDidTakeScreenshot:) name:UIApplicationUserDidTakeScreenshotNotification object:nil];
}

• 2.然后做监听的处理，绘制获取当前屏幕的上下文，输入图片

- (void)userDidTakeScreenshot:(NSNotification *)notification {
    UIImage *image = [self imageWithScreenshot];
    if(image) {
// WEGlobalShareView这个是绘制显示的效果图，页面不复杂，小编就没有放到这里来
        [WEGlobalShareView showWithDelegate:self andDetailImage:image];
    }
}
// 截取当前屏幕 ,返回截取到的图片
- (UIImage *)imageWithScreenshot {
    CGSize imageSize = CGSizeZero;
    UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;
    if (UIInterfaceOrientationIsPortrait(orientation)) {
        imageSize = [UIScreen mainScreen].bounds.size;
    } else {
        imageSize = CGSizeMake([UIScreen mainScreen].bounds.size.height, [UIScreen mainScreen].bounds.size.width);
    }
    // 绘制上下文
    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 (orientation == UIInterfaceOrientationLandscapeLeft) {
            CGContextRotateCTM(context, M_PI_2);
            CGContextTranslateCTM(context, 0, -imageSize.width);
        } else if (orientation == UIInterfaceOrientationLandscapeRight) {
            CGContextRotateCTM(context, -M_PI_2);
            CGContextTranslateCTM(context, -imageSize.height, 0);
        } else if (orientation == UIInterfaceOrientationPortraitUpsideDown) {
            CGContextRotateCTM(context, M_PI);
            CGContextTranslateCTM(context, -imageSize.width, -imageSize.height);
        }
        if ([window respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)]) {
            [window drawViewHierarchyInRect:window.bounds afterScreenUpdates:YES];
        } else {
            [window.layer renderInContext:context];
        }
        CGContextRestoreGState(context);
    }
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    NSData *imageData = UIImagePNGRepresentation(image);
    return [UIImage imageWithData:imageData];
}

• 3.最后拿到图片以后，进行分享页面即可；