The easiest way to scale image is to use UIImageView by setting its contentMode property.
If you have to use UIView to show the image, you may try to redraw the image in UIView.
1.subclass UIView
2.draw your image in drawRect
//the followed code draw the origin size of the image
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
[_yourImage drawAtPoint:CGPointMake(0,0)];
}
//if you want to draw as much as the size of the image, you should calculate the rect that the image draws into
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
[_yourImage drawInRect:_rectToDraw];
}
- (void)setYourImage:(UIImage *)yourImage
{
_yourImage = yourImage;
CGFloat imageWidth = yourImage.size.width;
CGFloat imageHeight = yourImage.size.height;
CGFloat scaleW = imageWidth / self.bounds.size.width;
CGFloat scaleH = imageHeight / self.bounds.size.height;
CGFloat max = scaleW > scaleH ? scaleW : scaleH;
_rectToDraw = CGRectMake(0, 0, imageWidth * max, imageHeight * max);
}