iphone缩略图处理

-(UIImage * ) generatePhotoThumbnail: (UIImage * ) image {    // Create a thumbnail version of the image for the event object.    CGSize size = image.size;    CGSize croppedSize;    CGFloat ratio = 64.0; //这个是设置转换后图片的尺寸大小    CGFloat offsetX = 0.0;    CGFloat offsetY = 0.0;    // check the size of the image, we want to make it    // a square with sides the size of the smallest dimension    if (size.width > size.height) {        offsetX = (size.height - size.width) / 2;        croppedSize = CGSizeMake(size.height, size.height);    } else {        offsetY = (size.width - size.height) / 2;        croppedSize = CGSizeMake(size.width, size.width);    }    // Crop the image before resize    CGRect clippedRect = CGRectMake(offsetX * -1, offsetY * -1, croppedSize.width, croppedSize.height);    CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], clippedRect);    // Done cropping    // Resize the image    CGRect rect = CGRectMake(0.0, 0.0, ratio, ratio);    UIGraphicsBeginImageContext(rect.size);    [        [UIImage imageWithCGImage: imageRef] drawInRect: rect];    UIImage * thumbnail = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();    // Done Resizing    return thumbnail;}

转载自：http://blog.sina.com.cn/s/blog_699ebf3d0100ob8h.html