截取当前在iOS上不显示的视图的屏幕截图 [英] Taking a screenshot of a view that is currently not on screen on iOS

问题描述

我正在尝试在两个ViewController之间进行转换.我的Transition类具有目标视图控制器的属性.当我尝试获取目标视图的屏幕截图时，我使用以下方法:

I'm trying to make a transition between two ViewControllers. My Transition class has a property for the destination view controller. When I try to get a screenshot of the destination's view, I use this method:

+ (UIImage *)renderImageFromView:(UIView *)view withRect:(CGRect)frame {
    // Create a new context the size of the frame
    UIGraphicsBeginImageContextWithOptions(frame.size, YES, 0);
    CGContextRef context = UIGraphicsGetCurrentContext();

    // Render the view 
    [view.layer renderInContext:context];

    // Get the image from the context
    UIImage *renderedImage = UIGraphicsGetImageFromCurrentImageContext();

    // Cleanup the context you created
    UIGraphicsEndImageContext();

    return renderedImage;
}

因此，当我想要图像时，我将执行以下操作:

So when I want the image, I'll do this:

UIImage *image = [UIImage renderImageFromView:destinationController.view withRect:destinationController.view.bounds];

我在带有橙色背景色和标签的空白UIViewController上尝试过.我得到了橙色背景色，但是没有得到在IB中创建的标签.有没有办法获取我计划显示的新视图的适当屏幕截图?谢谢！

I tried it on a blank UIViewController with an orange background color and a label. I get the orange background color, but I do not get the label that was created in IB. Is there a way to get a proper screenshot of the new view I plan on showing? Thanks!

推荐答案

您需要确保将视图的图层绘制到第一层.在 CALayer 上调用renderInContext只会递归地调用其他子 CALayer .您需要您的孩子 UIView 进行绘制，而不仅仅是使用 CALayer .

You need to make sure the view's layer is drawn to first. Calling renderInContext on a CALayer will only recursively call additional child CALayers. You need your child UIViews to draw themselves, not just using the CALayer.

尝试致电

[view drawrect:frame]; 

代替

[view.layer renderInContext:context];

只要您具有打开的图形上下文(此时需要执行此操作)， drawrect 就应该直接在其中绘制图形.

As long as you have an open graphics context(which you do at that point), drawrect should draw directly into that.

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