UIImageViews以自动布局的代码嵌入UIScrollView中

Question

I am currently having trouble with my iOS app and Autolayout. I want to let the user scroll photos from Tumblr in a UIScrollView (similar to Photos app, when scrolling your library). So when my ImageViewController gets on screen, it has an array of posts but no data for the images yet. My problem is the following :

In my scrollView, I want to add as many UIImageViewS as needed, and I would like them to be all the same size. How should I do it? I tried many (probably bad designed :-/) ways, like initwithframe: with auto layout on and keeping a reference to them in a NSMutableArray ...

My goal now is to add them to my scrollView in viewDidLoad and have correct constraints set.

Thanks for your help and sorry for my poor English

EDIT

OK I solved my problem: I used a nice scrollView and set its constraints with auto layout in viewWillAppear

Here is the code for those interested (sorry for layout) : - (void)viewWillAppear:(BOOL)animated {

[super viewWillAppear:animated];
[self downloadPhotos];
[self.scrollView setContentOffset:CGPointMake(self.selectedImageIndex * self.scrollView.frame.size.width, 0) animated:NO];

// Add UIImageViewS to self.scrollView with constraints and so on...
NSMutableDictionary *viewsDictionnary = [[NSMutableDictionary alloc] init];
NSMutableString *imageViewsString = [[NSMutableString alloc] init];
NSMutableArray *imageViews = [[NSMutableArray alloc] init];

for (int i = 0; i < self.fetchedResultsController.fetchedObjects.count; i++) {
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:self.scrollView.bounds];
    imageView.image = [UIImage imageNamed:@"placeholder_imageView"];
    imageView.contentMode = UIViewContentModeScaleAspectFit;
    imageView.translatesAutoresizingMaskIntoConstraints = NO;
    [self.scrollView addSubview:imageView];

    [imageViews addObject:imageView];
    [viewsDictionnary setObject:imageView forKey:[NSString stringWithFormat:@"imageView%d", i]];
    [imageViewsString appendString:[NSString stringWithFormat:@"[imageView%d]", i]];
    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:imageView attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0]];
    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:imageView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0.0]];
    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:imageView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0.0]];
}
self.imageViews = imageViews;
NSString *horizontal = [NSString stringWithFormat:@"H:|%@|", imageViewsString];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:horizontal options:0 metrics:0 views:viewsDictionnary]];
[self.scrollView setContentOffset:CGPointMake(self.selectedImageIndex * self.scrollView.frame.size.width, 0) animated:NO];

}

Answer 1

 -(void)viewDidLoad 
 {
      [super viewDidLoad];

      float posX = 0.0 , poxY = 0.0;

      float sizeWidth = 100 , sizeHeight = 200;

      float scrollContentWidth = 320.0;

      scrollview.showsHorizontalScrollIndicator=YES;
      scrollview.scrollEnabled=YES;
      scrollview.userInteractionEnabled=YES;
      self.scrollView.pagingEnabled = TRUE;

      for(int i=0;i<[imageArray count];i++)
      {
           NSString *imageURL = [imageArray objectAtIndex:i];

           UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(posX,posY,sizeWidth,sizeHeight)];

           [imageView setImage:[UIImage imageWithContentsOfFile:imageURL]];

           [self.scrollView addSubview:imageView];

           [imageView addConstraint:
           [NSLayoutConstraint constraintWithItem:imageView 
           attribute:NSLayoutAttributeWidth
           relatedBy:NSLayoutRelationEqual
           toItem:imageView 
           attribute:NSLayoutAttributeWidth
           multiplier:1
           constant:100]];

           [imageView  addConstraint:
           [NSLayoutConstraint constraintWithItem:imageView 
           attribute:NSLayoutAttributeHeight
           relatedBy:NSLayoutRelationEqual
           toItem:imageView 
           attribute:NSLayoutAttributeHeight
           multiplier:1
           constant:200]];

           [self.scrollView setContentSize:CGSizeMake(480.0,scrollContentWidth)];

           scrollContentWidth=scrollContentWidth+320.0;

           posX = posX + 320.0;
      }
 }

Hope it will help you.

Answer 2

I recommend not using a scrollView but using a collectionView instead (iOS 6 and above). You will probably insist that you need to use iOS 5 or iOS 4. Make things easy for yourself, collectionViews make memory management easy and if you plan on loading a lot of photos in view, just go with collection views. You can then create a collectionViewCell which will have a UIImageView. The UIImageView will be only one size, you can then set its image scaling propery to scale to fit so no matter what shape or size, the images will fit in the image view and not be distorted. Do some research on colletion views, heck, there probably is a tutorial you can use to load images from the internet and display them using a collection view.