iOS 图片比例缩放

方法

//Resize image

- (UIImage *)resizeImage:(UIImage *)image
             withQuality:(CGInterpolationQuality)quality
                    rate:(CGFloat)rate
{
	UIImage *resized = nil;
	CGFloat width = image.size.width * rate;
	CGFloat height = image.size.height * rate;

	UIGraphicsBeginImageContext(CGSizeMake(width, height));
	CGContextRef context = UIGraphicsGetCurrentContext();
	CGContextSetInterpolationQuality(context, quality);
	[image drawInRect:CGRectMake(0, 0, width, height)];
	resized = UIGraphicsGetImageFromCurrentImageContext();
	UIGraphicsEndImageContext();

	return resized;
}

　　

使用

UIImageView *theImageView = [[UIImageView alloc]init];

    theImageView.frame = CGRectMake(0, 64, 320, 400);

    UIImage *aImage = [UIImage imageNamed:@"shenlin.png"];

    UIImage *resizeImage = [self resizeImage:aImage withQuality:kCGInterpolationNone rate:0.2];
    theImageView.image = resizeImage;
    theImageView.frame = CGRectMake(0, 64, resizeImage.size.width, resizeImage.size.height);
    NSLog(@"%@",NSStringFromCGSize(resizeImage.size));

    [self.view addSubview:theImageView];