How Do I Take a Screen Shot of a UIView?

Question

I am wondering how my iPhone app can take a screen shot of a specific UIView as a UIImage.

I tried this code but all I get is a blank image

Answer 1

You need to capture the key window for a screenshot or a UIView. You can do it in Retina Resolution using UIGraphicsBeginImageContextWithOptions and set its scale parameter 0.0f. It always captures in native resolution (retina for iPhone 4 and later).

This one does a full screen screenshot (key window)

UIWindow *keyWindow = [[UIApplication sharedApplication] keyWindow];
CGRect rect = [keyWindow bounds];
UIGraphicsBeginImageContextWithOptions(rect.size,YES,0.0f);
CGContextRef context = UIGraphicsGetCurrentContext();
[keyWindow.layer renderInContext:context];   
UIImage *capturedScreen = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

This code capture a UIView in native resolution

CGRect rect = [captureView bounds];
UIGraphicsBeginImageContextWithOptions(rect.size,YES,0.0f);
CGContextRef context = UIGraphicsGetCurrentContext();
[captureView.layer renderInContext:context];   
UIImage *capturedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

This saves the UIImage in jpg format with 95% quality in the app's document folder if you need to do that.

NSString  *imagePath = [NSHomeDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:@"Documents/capturedImage.jpg"]];    
[UIImageJPEGRepresentation(capturedImage, 0.95) writeToFile:imagePath atomically:YES];