UIScrollView Autolayout prevent from scrolling vertically - uiscrollview

Question

I'm wondering how to crop image inside UIscrollView with autolayout
I'm trying to make UIscrollView scroll only horizontally. if image is higher than view height it should be cropped. I've tried a lot properties but can't make all images inside uiscrollview same height as view to avoid scrolling vertically.
Do i miss something?
#import "WelcomeController.h"
#interface WelcomeController ()
#property (strong, nonatomic) UIScrollView *scrollView;
#property (nonatomic,strong) NSArray *contentList;
#end
#implementation WelcomeController
#synthesize contentList =_contentList;
- (void)updateUI
{
UIScrollView* sv = self.scrollView;
id previousLab = nil;
for (UIView *lab in _contentList) {
lab.translatesAutoresizingMaskIntoConstraints = NO;
lab.backgroundColor = [UIColor blackColor];
lab.contentMode = UIViewContentModeScaleAspectFit;
[sv addSubview:lab];
[sv addConstraints:
[NSLayoutConstraint constraintsWithVisualFormat:#"V:|[lab]|"
options:0 metrics:nil
views:#{#"lab":lab}]];
if (!previousLab) { // first one, pin to top
[sv addConstraints:
[NSLayoutConstraint constraintsWithVisualFormat:#"H:|[lab]"
options:0 metrics:nil
views:#{#"lab":lab}]];
} else { // all others, pin to previous
[sv addConstraints:
[NSLayoutConstraint
constraintsWithVisualFormat:#"H:[prev][lab]"
options:0 metrics:nil
views:#{#"lab":lab, #"prev":previousLab}]];
}
previousLab = lab;
}
// last one, pin to bottom and right, this dictates content size height
[sv addConstraints:
[NSLayoutConstraint constraintsWithVisualFormat:#"V:|[lab]|"
options:0 metrics:nil
views:#{#"lab":previousLab}]];
[sv addConstraints:
[NSLayoutConstraint constraintsWithVisualFormat:#"H:[lab]|"
options:0 metrics:nil
views:#{#"lab":previousLab}]];
}
-(void)setContentList:(NSArray *)contentList
{
_contentList = contentList;
[self updateUI];
}
- (void)setupScrollView
{
UIScrollView* sv = [UIScrollView new];
sv.backgroundColor = [UIColor redColor];
sv.translatesAutoresizingMaskIntoConstraints = NO;
sv.pagingEnabled = YES;
sv.showsHorizontalScrollIndicator =NO;
sv.showsVerticalScrollIndicator = NO;
sv.bounces =NO;
[self.view addSubview:sv];
[self.view addConstraints:
[NSLayoutConstraint constraintsWithVisualFormat:#"H:|[sv]|"
options:0 metrics:nil
views:#{#"sv":sv}]];
[self.view addConstraints:
[NSLayoutConstraint constraintsWithVisualFormat:#"V:|[sv]|"
options:0 metrics:nil
views:#{#"sv":sv}]];
self.scrollView = sv;
}
- (void)viewDidLoad
{
[super viewDidLoad];
[self setupScrollView];
//for testing
UIImageView *image1=[[UIImageView alloc] initWithImage:[UIImage imageNamed:#"welcome1.jpg"]];
UIImageView *image2=[[UIImageView alloc] initWithImage:[UIImage imageNamed:#"welcome2.jpg"]];
UIImageView *image3=[[UIImageView alloc] initWithImage:[UIImage imageNamed:#"welcome3.jpg"]];
self.contentList = [NSArray arrayWithObjects:image1,image2,image3,nil];
}
#end

Answer 1

Have you tried setting the height of the scroll view explicitly?
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"V:[_sv(123)]" options:0 metrics:nil views:views]];
You would need to replace the height above (123) with the height you need, obviously, as well as views.

Answer 2

Autolayout automatically manages the UIScrollView's contentSize (the scrollable area). So if you stick a subview in there with an intrinsic size that is larger than the height, it will increase the contentSize. I can think of two things:
Stick images in a plain UIView with the same height as the scrollview.
Subclass the UIImageView and override the intrinsicContentSize method to return a fixed height for all images. This seems like a poor solution, though.

Answer 3

I think you should be able to set the image view's frames to a fixed height (via constraints). Then add constraints to have the image views top and bottom fixed with x constant from the scrollview.
This will let the scrollview know its exact content size to use. As long as its frame, then, (determined by whatever constraints you give it in relation to its superview) is >= the image view's fixed heights, it won't scroll vertically.