Question

Im trying to save a screen from my app with th use of a button rather than the home button/on off affair. Im getting an error with code using self.

“Property Window not found on object of type “…my view controller”

- (IBAction)saveto:(id)sender {
if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
    UIGraphicsBeginImageContextWithOptions(self.window.bounds.size, NO, [UIScreen mainScreen].scale);
else
    UIGraphicsBeginImageContext(self.window.bounds.size);
[self.window.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSData * data = UIImagePNGRepresentation(image);
[data writeToFile:@"my.png" atomically:YES];

(Image view is declared as outlet in .h)

I know im missing something basic here but cant figure it out, any help greatfully received

Answer 1

Its self.view.window I’m pretty sure. 🙂

- (IBAction)saveto:(id)sender {
    if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
        UIGraphicsBeginImageContextWithOptions(self.view.window.bounds.size, NO, [UIScreen mainScreen].scale);
    else
        UIGraphicsBeginImageContext(self.window.bounds.size);
    [self.view.window.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    NSData * data = UIImagePNGRepresentation(image);
    [data writeToFile:@"my.png" atomically:YES];
}

Window is a property on UIView.

http://developer.apple.com/library/ios/#documentation/uikit/reference/uiview_class/uiview/uiview.html

window The receiver’s window object, or nil if it has none.
(read-only)

@property(nonatomic, readonly) UIWindow *window Discussion This
property is nil if the view has not yet been added to a window.

Availability Available in iOS 2.0 and later. Declared In UIView.h

UIViewController doesn’t have a window property. However it has a view property which does have a window property 🙂

http://developer.apple.com/library/ios/#DOCUMENTATION/UIKit/Reference/UIViewController_Class/Reference/Reference.html