Question

I need to form an image by composing some visual elements and save it on disk. The question is: how to “screenshot” a certain area of a view? Possibly a view that is not visible, so the procedure can be executed unnoticed?

Answer 1

This code snippet shows how to render a view to a UIImage:

UIGraphicsBeginImageContext(myView.bounds.size);
[myView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

And this snippet shows how to save a UIImage as a JPEG or a PNG:

NSString  *pngPath = [NSHomeDirectory() 
    stringByAppendingPathComponent:@"Documents/Test.png"];
NSString  *jpgPath = [NSHomeDirectory() 
    stringByAppendingPathComponent:@"Documents/Test.jpg"];
[UIImageJPEGRepresentation(viewImage, 1.0) writeToFile:jpgPath atomically:YES];
[UIImagePNGRepresentation(viewImage) writeToFile:pngPath atomically:YES];