iOS 图片剪切和压缩的几个方法

// 图片剪切

- (UIImage*)clipImageWithImage:(UIImage*)image inRect:(CGRect)rect {
    CGImageRef imageRef = CGImageCreateWithImageInRect(image.CGImage, rect);

UIGraphicsBeginImageContext(image.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextDrawImage(context, rect, imageRef);
    UIImage* clipImage = [UIImage imageWithCGImage:imageRef];
//    CGImageCreateWithImageInRect(CGImageRef  _Nullable image, <#CGRect rect#>)
//    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();      // 不同的方式
    UIGraphicsEndImageContext();
    
//    NSData* data = [NSData dataWithData:UIImagePNGRepresentation(clipImage)];
//    BOOL flag = [data writeToFile:@"/Users/gua/Desktop/Image/后.png" atomically:YES];
//    GGLogDebug(@"========压缩后=======%@",clipImage);
    
    return clipImage;
}

// 图片压缩
- (UIImage*)imageCompressImage:(UIImage *)sourceImage targetWidth:(CGFloat)defineWidth {
    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    CGFloat targetWidth = defineWidth;
    CGFloat targetHeight = (targetWidth / width) * height;
    UIGraphicsBeginImageContext(CGSizeMake(targetWidth, targetHeight));
    [sourceImage drawInRect:CGRectMake(0,0,targetWidth, targetHeight)];
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return newImage;
}