iOS截取圖片方法

-(UIImage *)getImageFromImage :(UIImage*)BIGimg{

    CGRect myImageRect = CGRectMake(0, BIGimg.size.height/2 - BIGimg.size.width/2, BIGimg.size.width, BIGimg.size.width);//這個CGRectMake 決定截圖位置

    UIImage* bigImage= BIGimg;

    CGImageRef imageRef = bigImage.CGImage;

    CGImageRef subImageRef = CGImageCreateWithImageInRect(imageRef, myImageRect);

    CGSize size;

    size.width = 60.0;                         //這兩個量須要設置   也就是新的圖片的大小

    size.height = 60.0;                       

    // 截取用的方法

    UIGraphicsBeginImageContext(size);

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextDrawImage(context, myImageRect, subImageRef);

    UIImage* smallImage = [UIImage imageWithCGImage:subImageRef];

    UIGraphicsEndImageContext();

    return smallImage;

}