以高质量的iOS截图

我正在以这种方式截取我的iPad 3屏幕：

UIGraphicsBeginImageContext(self.view.frame.size); [self.view.layer renderInContext:UIGraphicsGetCurrentContext()]; UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; int num = arc4random() % 100000000000000; NSString* path = [documentsDirectory stringByAppendingPathComponent: [NSString stringWithFormat:@"%dtest.png", num]]; NSData* data = UIImagePNGRepresentation(viewImage); [data writeToFile:path atomically:YES]; 

问题是我有一个重大的质量损失。 我可以看到像素，但它是一个iPad 3，所以它怎么样？

Answer 1

 - (UIImage*)screenshot { // Create a graphics context with the target size // On iOS 4 and later, use UIGraphicsBeginImageContextWithOptions to take the scale into consideration // On iOS prior to 4, fall back to use UIGraphicsBeginImageContext CGSize imageSize = [[UIScreen mainScreen] bounds].size; if (NULL != UIGraphicsBeginImageContextWithOptions) UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0); else UIGraphicsBeginImageContext(imageSize); CGContextRef context = UIGraphicsGetCurrentContext(); // Iterate over every window from back to front for (UIWindow *window in [[UIApplication sharedApplication] windows]) { if (![window respondsToSelector:@selector(screen)] || [window screen] == [UIScreen mainScreen]) { // -renderInContext: renders in the coordinate space of the layer, // so we must first apply the layer's geometry to the graphics context CGContextSaveGState(context); // Center the context around the window's anchor point CGContextTranslateCTM(context, [window center].x, [window center].y); // Apply the window's transform about the anchor point CGContextConcatCTM(context, [window transform]); // Offset by the portion of the bounds left of and above the anchor point CGContextTranslateCTM(context, -[window bounds].size.width * [[window layer] anchorPoint].x, -[window bounds].size.height * [[window layer] anchorPoint].y); // Render the layer hierarchy to the current context [[window layer] renderInContext:context]; // Restore the context CGContextRestoreGState(context); } } // Retrieve the screenshot image UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return image; } 

更多信息请阅读本技术报告： 技术问答QA1703 UIKit应用程序中的屏幕捕获

Answer 2

从文档：

 UIGraphicsBeginImageContextWithOptions Creates a bitmap-based graphics context with the specified options. void UIGraphicsBeginImageContextWithOptions( CGSize size, BOOL opaque, CGFloat scale ); 

然后 ：

 UIGraphicsBeginImageContextWithOptions(self.view.frame.size,NO,2.0); 

Answer 3

你的大小是错误的，使用这个：

 CGRect screenBounds = [[UIScreen mainScreen] bounds]; CGFloat screenScale = [[UIScreen mainScreen] scale]; CGSize screenSize = CGSizeMake(screenBounds.size.width * screenScale, screenBounds.size.height * screenScale); UIGraphicsBeginImageContext(screenSize); //screenshot code..