How to programmatically take a screenshot in iOS? - ios

Question

How can I programmatically take a screenshot of the entire screen (iPhone) and save it to the photo library in iOS? There is nothing on the screen other than some labels and a button.
The button is named "ScreenshotButton" that needs to trigger this.
Do I still need to import QuartzCore?
Where exactly would I need to place the Screenshot Function in the ViewController?

Answer 1

You need CoreGraphics. Here's the code I use within the IBAction of a button:
CGRect rect = [[UIScreen mainScreen] bounds];
CGSize imageSize = rect.size;
UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSaveGState(ctx);
CGContextConcatCTM(ctx, [self.view.layer affineTransform]);
if ([self.view respondsToSelector:#selector(drawViewHierarchyInRect:afterScreenUpdates:)]) { // iOS 7+
[self.view drawViewHierarchyInRect:self.view.bounds afterScreenUpdates:YES];
} else { // iOS 6
[self.view.layer renderInContext:ctx];
}
screengrab = UIGraphicsGetImageFromCurrentImageContext();
CGContextRestoreGState(ctx);
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(screengrab, nil, nil, nil);
I define static UIImage *screengrab; at the top of my code after #implementation.
You should use Analyze to check for leaks -- I don't have any myself in this code, but CG code always seems to create some.

Answer 2

Hereunder the class used to take snapshot of a view :
#import "ScreenSnapshot.h"
#import <QuartzCore/QuartzCore.h>
#implementation ScreenSnapshot
static NSUInteger imgNumber;
+ (void)initialize { imgNumber = 0; }
+ (void)saveScreenSnapshot:(UIView *)view {
UIImage * img = [self screenSnapshotOf:view];
NSData * data = UIImagePNGRepresentation(img);
imgNumber += 1;
NSString * fullPath = [NSString stringWithFormat:#"%#/Documents/img_%ld.png",NSHomeDirectory(),imgNumber];
[data writeToFile:fullPath
atomically:YES];
}
+ (UIImage *)screenSnapshotOf:(UIView *)view {
UIGraphicsBeginImageContext(view.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[view.layer renderInContext:context];
UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
#end
Copy this code as is in a new class called 'ScreenSnapshot'.
In your "ScreenshotButton" action, write:
[ScreenSnapshot saveScreenSnapshot:self.view];
...after having imported "ScreenSnapshot.h".
You can replace the location used in my code to store the images and you'll be able to programmatically take a screenshot in iOS.