UIImageView using UIViewContentModeScaleAspectFit in ScrollView is not center

Question

Thanks a lot! Please help!

I hava a scrollView in a UIView and a imageView in the ScrollView. they have same size. and here are the LOGs of the scrollView and imageview

and I have not used autoLayout constrains between uiview and scroll View as well as scrollview and UIimageView

the code are:

- (void)setupScrollView
{
    CGRect frame = CGRectMake(0, 0, self.scrollViewSizeView.frame.size.width, self.scrollViewSizeView.frame.size.height);
    _colorScrollView = [[ColorScrollView alloc]initWithFrame:frame andUIImage:self.image];
    [self.scrollViewSizeView addSubview:self.colorScrollView];
}


- (instancetype)initWithFrame:(CGRect)frame andUIImage:(UIImage *)image
{
    self = [super initWithFrame:frame];
    if (self)
    {
        self.contentSize = frame.size;
        _imageView = [[ColorImageView alloc]initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];
        self.imageView.image = image;
        [self addSubview:self.imageView];
    }
    return self;
}

scrollView:

<ColorScrollView: 0x7fee13746dc0; baseClass = UIScrollView; frame = (0 0; 600 436); clipsToBounds = YES; gestureRecognizers = <NSArray: 0x7fee13748270>; layer = <CALayer: 0x7fee13741330>; contentOffset: {0, 0}; contentSize: {600, 436}>

imageView:

 <ColorImageView: 0x7fee13747e00; baseClass = UIImageView; frame = (0 0; 600 436); opaque = NO; layer = <CALayer: 0x7fee1370fc50>>

the imageView content mode is UIViewContentModeScaleAspectFit. I want the image in imageView is center. but it is not. it look like it prefer to stay at the right side. sorry that I don't have enough reputation to post a image:

it looks this (* means transparent)

*****this is the image area

Assuming there is no random white space on the left side of your image, everything should be fine. I suspect that it may be a layout issue, and that your image view is getting pushed to the right, your image view is getting shifted from layout constraints. — Nate Lee, Jan 18 '15 at 13:32
@YuchenZhong I have not used autoLayout constraint between scrollView and imageView — Qiufang Fang, Jan 18 '15 at 13:43
@NateLee thanks for your help. Could you please give me more hint？ — Qiufang Fang, Jan 18 '15 at 13:44
Are you able to give us a snippet of how you set up the structure? I mean some code snippet. — Yuchen, Jan 18 '15 at 13:48

score 0 · Answer 1 · answered Jan 18 '15 at 13:29

0

The only thing that come to my mind is add a uiview in the uiscrollview and then add your image in to that uiview

if you could give us some of your constraint you use that could help us

answered Jan 18 '15 at 13:29

Ali Riahipour

524
6
20

I need to zoom the imageView. – Qiufang Fang Jan 18 '15 at 13:31
the scrollView is programmatically add to the uiview – Qiufang Fang Jan 18 '15 at 13:33
@QiufangFang, No I mean add 2 uiview, uiview -> uiscrollview -> uiview -> imageview – Ali Riahipour Jan 18 '15 at 13:36
thanks a lot.But why should we do this? Can the image just be center in the imageView? – Qiufang Fang Jan 18 '15 at 13:40
@QiufangFang I think this [link](http://natashatherobot.com/ios-autolayout-scrollview/) will help – Ali Riahipour Jan 18 '15 at 13:47
thanks for your help. I have read this page before.Bur it seems it does not fit my problem. – Qiufang Fang Jan 18 '15 at 13:49
@Ali RP. `UIImageView` is subclass from `UIView`. – Yuchen Jan 18 '15 at 13:52
@YuchenZhong I know that, but i think the OP has some other view in the scrollview, so that views cause the white spaces – Ali Riahipour Jan 18 '15 at 13:54
i have not other view in scrollview .and the problem is if the aspect ratio of the image is close to the aspect ratio of the imageView. then we have no problem. – Qiufang Fang Jan 18 '15 at 14:02

score 0 · Answer 2 · edited May 23 '17 at 12:12

From your commends for @Ali RP's answer, "if the aspect ratio of the image is close to the aspect ratio of the imageView. then no problem." I think your problem is because of UIViewContentModeScaleAspectFit. You have some white space of both size of the image.

UIViewContentModeScaleAspectFit

Scales the content to fit the size of the view by maintaining the aspect ratio. Any remaining area of the view’s bounds is transparent.

And the reason why it is not centred is because the image you are using is too big I guess and right part of the subview is cropped. Try with a smaller one and one with different aspect ratio for debugging. For example, you should have some images with width > height and some with height > width.

Also see this one: Difference between UIViewContentModeScaleAspectFit and UIViewContentModeScaleToFill?

UIImageView using UIViewContentModeScaleAspectFit in ScrollView is not center

2 Answers2