剪裁图片

-(UIImage *)imageWithImage:(UIImage *)image sizeScaletoSize:(CGSize)newSize;

{

// create a graphics image context

UIGraphicsBeginImageContext(newSize);

// tell the old image to draw in this new context ,with the desired new size

[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];

//get the new image from the context

UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

//end the context

UIGraphicsEndImageContext();

//  return the new image

return newImage;

}