监听手机截屏事件

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原文地址: http://blog.csdn.net/cocos2der/article/details/51780954

今天无意中在百度地图中截屏路线的时候，顶部出现提示我的截屏信息。这细节挺好的，省去我后面需要使用该截屏的繁琐步骤。刚好手头空闲会，我也写个玩玩。哈哈哈~~

截屏在iOS7以前是需要使用小技巧来获取用户截屏事件的，iOS7之后，apple开放了用户截屏通知事件，所以现在做起来还是挺方便的。

// This notification is posted after the user takes a screenshot (for example by pressing both the home and lock screen buttons)
@available(iOS 7.0, *)
public let UIApplicationUserDidTakeScreenshotNotification: String

注册通知

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(ViewController.userDidTakeScreenshot), name: UIApplicationUserDidTakeScreenshotNotification, object: nil)

代码实现（swift）

/// 用户截屏完毕
func userDidTakeScreenshot() {
// 当前屏幕的image
// 注意：为什么不直接从相册读取截屏图像
//（万一用户直接拒绝可权限你不跪了，何况截屏之后，用户可不知道你会提示，第一反应肯定拒绝读取相册的权限）
let image = imageWithScreenshot()

let imageView = UIImageView(frame: CGRect(x: 50, y: 50, width: 320, height: 640))
imageView.image = image
self.view.addSubview(imageView)
}

/// 获取当前屏幕图片
func imageWithScreenshot() -> UIImage? {
let imageData = dataWithScreenshotInPNGFormat()
return UIImage(data: imageData)
}

/// 截取当前屏幕
func dataWithScreenshotInPNGFormat() -> NSData {
var imageSize = CGSizeZero
let screenSize = UIScreen.mainScreen().bounds.size
let orientation = UIApplication.sharedApplication().statusBarOrientation
if UIInterfaceOrientationIsPortrait(orientation) {
imageSize = screenSize
} else {
imageSize = CGSizeMake(screenSize.height, screenSize.width)
}

UIGraphicsBeginImageContextWithOptions(imageSize, false, 0)
let context = UIGraphicsGetCurrentContext()

for 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 == UIInterfaceOrientation.LandscapeLeft {
CGContextRotateCTM(context, CGFloat(M_PI_2))
CGContextTranslateCTM(context, 0, -imageSize.width)
} else if orientation == UIInterfaceOrientation.LandscapeRight {
CGContextRotateCTM(context, -CGFloat(M_PI_2))
CGContextTranslateCTM(context, -imageSize.height, 0)
} else if (orientation == UIInterfaceOrientation.PortraitUpsideDown) {
CGContextRotateCTM(context, CGFloat(M_PI))
CGContextTranslateCTM(context, -imageSize.width, -imageSize.height)
}
if window.respondsToSelector(#selector(UIView.drawViewHierarchyInRect(_:afterScreenUpdates:))) {
window.drawViewHierarchyInRect(window.bounds, afterScreenUpdates: true)
} else {
window.layer.renderInContext(context!)
}
CGContextRestoreGState(context);
}
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

return UIImagePNGRepresentation(image)!
}

注意：为什么不直接从相册读取截屏图像？

万一用户直接拒绝可权限你不跪了，何况截屏之后，用户可不知道你会提示，第一反应肯定拒绝读取相册的权限。