CODEWITHSUNDEEP
iosscreenshot
Jiulong Zhao
Jiulong Zhao

Reputation: 1363

taking a screenshot before my IOS app launch

Is it possible taking a screenshot before my IOS app launched.

I can simply take screenshot of my app's main view by:

    UIGraphicsBeginImageContext(self.view.frame.size);
    [self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil);

I also tried this method UIKit way:

    // 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();

    UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);

    UIGraphicsEndImageContext();

They all works on capturing screenshot of my app.

How may I capture the screenshot (of the moment) BEFORE my app launched.

I even add the second sample code to the begin of main.m, it does NOT work. (a full screen blank white image was saved)

I want to use the screenshot as the background picture of my app :) my app is running...

Upvotes: 1

Views: 732

Answers (2)

box86rowh
box86rowh

Reputation: 3415

http://graphicssoft.about.com/od/screencapture/qt/screen-shot-ipod-iphone.htm

This is a quick and easy approach to saving a shot of what is being shown on your device.

Upvotes: -1

Kaan Dedeoglu
Kaan Dedeoglu

Reputation: 14841

Your app's code does not get executed before the app launches. I don't know how/why you want to achieve this.

Upvotes: 3

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