- (UIImage *)ct_imageFromImage:(UIImage *)image inRect:(CGRect)rect{
//把像 素rect 转化为 点rect（如无转化则按原图像素取部分图片）
CGFloat scale = [UIScreen mainScreen].scale;
CGFloat x= rect.origin.x*scale,y=rect.origin.y*scale,w=rect.size.width*scale,h=rect.size.height*scale;
CGRect dianRect = CGRectMake(x, y, w, h);
//截取部分图片并生成新图片
CGImageRef sourceImageRef = [image CGImage];
CGImageRef newImageRef = CGImageCreateWithImageInRect(sourceImageRef, dianRect);
UIImage *newImage = [UIImage imageWithCGImage:newImageRef scale:[UIScreen mainScreen].scale orientation:UIImageOrientationUp];
return newImage;
}