uiview内的uiview也位于按钮内，显示uiimage模糊

Question

So I have a button with a custom uiview that contain a uiimageview.

UIButton *myButton = [[UIButton alloc] init];
myButton.frame = CGRectMake(0, 0, 29, 29);

UIView  *myView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 29, 29)];


UIImage *myImage = [UIImage imageNamed:@"sexy-pic-of-me"];
UIImageView *myImageView = [[UIImageView alloc] initWithImage:myImage];
myImageView.frame = CGRectMake(0,0,29,29);

[myView addSubview:myImageView];
[myButton addSubview:myView];

[self.view addSubview: myButton];

My image is blurry no matter how much in increase or decrease the size. What am i doing wrong here?

Answer 1

Try setting a content mode ie:

myImageView.contentMode = UIViewContentModeScaleAspectFit;

Read more about content modes: https://developer.apple.com/library/ios/documentation/uikit/reference/UIView_Class/UIView/UIView.html#//apple_ref/c/tdef/UIViewContentMode

UIViewContentMode
Options to specify how a view adjusts its content when its size changes.

typedef enum {
   UIViewContentModeScaleToFill,
   UIViewContentModeScaleAspectFit,
   UIViewContentModeScaleAspectFill,
   UIViewContentModeRedraw,
   UIViewContentModeCenter,
   UIViewContentModeTop,
   UIViewContentModeBottom,
   UIViewContentModeLeft,
   UIViewContentModeRight,
   UIViewContentModeTopLeft,
   UIViewContentModeTopRight,
   UIViewContentModeBottomLeft,
   UIViewContentModeBottomRight,
} UIViewContentMode;

Answer 2

The other folks have mentioned two of the possible causes of fuzziness

• the image size doesn't match the frame size, resulting in scaling
• the image aspect ratio is being adjusted due to the content mode

The third possible cause is the use of odd numbers in the frame. From my experience, if the center.x and/or center.y of a UIView is not a whole number, then fuzziness results. For example, if you set the frame as

someView.frame = CGRect( 100, 100, 29, 29 );

then things get fuzzy because the center point of said view will be CGPoint( 114.5, 114.5 ) . This problem is mainly seen on the non-retina devices. Retina devices have two pixels per point, so half-a-point coordinates are ok, but other off-grid coordinates could still cause fuzziness.