如何选择一个UIImage的区域，然后创建一个新的区域？

Question

是有选择的UIImage实例的一个区域，然后从它创建一个新的形象的一种简单的方法？我尝试使用平移手势识别器获取用户选择的坐标。但有了这个选项，现在可以看到反馈，我也必须转换坐标。是否有一个很好的插件或最佳做法？

Answer 1

试试这个：

UIGraphicsBeginImageContext(self.view.bounds.size); 
// retrieve the current graphics context 
    CGContextRef context = UIGraphicsGetCurrentContext(); 
// render view into context 
    [self.view.layer renderInContext:context]; 
// create image from context 
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); 
    image=[self cropImage:image]; 
    UIGraphicsEndImageContext(); 

    - (UIImage *)cropImage:(UIImage *)oldImage { 
     CGSize imageSize = oldImage.size; 
     UIGraphicsBeginImageContextWithOptions(CGSizeMake(imageSize.width,imageSize.height - 150),NO,0.); //set your height and width 
      [oldImage drawAtPoint:CGPointMake(0, -80) blendMode:kCGBlendModeCopy alpha:1.]; 
      UIImage *croppedImage = UIGraphicsGetImageFromCurrentImageContext(); 
      UIGraphicsEndImageContext(); 
      return croppedImage; 
    } 

Answer 2

像这样：

CGImageRef imageRef = CGImageCreateWithImageInRect([bigImage CGImage], cropRect); 
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef]; 
CGImageRelease(imageRef);