如何根據圖像的交集區域來屏蔽圖像[上下文]？

Question

兩個圖像上下文不在同一位置，我希望其中一個圖像上下文根據其交集區域被屏蔽

Answer 1

UIImage *image1, *image2; 

    /* .... */ 

    CALayer *maskLayer = [[CALayer alloc] init]; 
    [maskLayer setFrame:[image1 convertRect:image2.bounds fromView:image2]]; 
    maskLayer.backgroundColor=[[UIColor blackColor] CGColor]; 
    image1.layer.mask=maskLayer; 
    [maskLayer release]; 

    maskLayer = [[CALayer alloc] init]; 
    [maskLayer setFrame:[image2 convertRect:image1.bounds fromView:image1]]; 
    maskLayer.backgroundColor=[[UIColor blackColor] CGColor]; 
    image2.layer.mask=maskLayer; 
    [maskLayer release];