ScrollView image addSubview issue - ios

Question

I'm trying to add an imageView in the ScrollView but I always get the ScrollView empty. Please where would be my issue? While I have added the delegate method <UIScrollViewDelegate> also made the connection in the storyboard.
My code:
- (void) viewDidLoad {
[super viewDidLoad];
[self slider];
}
-(void) slider {
_scrlView = [[UIScrollView alloc]init];
_scrlView.backgroundColor = [UIColor blackColor];
_scrlView.pagingEnabled = YES;
_scrlView.delegate = self;
_scrlView.showsHorizontalScrollIndicator = false;
_scrlView.layer.cornerRadius = 2;
_scrlView.contentSize = CGSizeMake(_scrlView.frame.size.width * 3, _scrlView.frame.size.height);
_img1 = [[UIImageView alloc] initWithFrame:CGRectMake((_scrlView.frame.size.width*0),0,_scrlView.frame.size.width,_scrlView.frame.size.height)];
_img2 = [[UIImageView alloc] initWithFrame:CGRectMake((_scrlView.frame.size.width*1),0,_scrlView.frame.size.width,_scrlView.frame.size.height)];
_img3 = [[UIImageView alloc] initWithFrame:CGRectMake((_scrlView.frame.size.width*2),0,_scrlView.frame.size.width,_scrlView.frame.size.height)];
_img1 = [[UIImageView alloc]initWithImage:[UIImage imageNamed:#"1234.jpg"]];
_img2 = [[UIImageView alloc]initWithImage:[UIImage imageNamed:#"1234.jpg"]];
_img3 = [[UIImageView alloc]initWithImage:[UIImage imageNamed:#"1234.jpg"]];
[_scrlView addSubview:_img1];
[_scrlView addSubview:_img2];
[_scrlView addSubview:_img3];
}

Answer 1

First, you don't add the scrollView to any view, so it won't be presented on screen.
Second, this:
_scrlView = [[UIScrollView alloc]init];
creates a scrollView with CGRectZero which is the same like writing:
_scrlView = [[UIScrollView alloc] initWithFrame:CGRectMake(0,0,0,0)];
This means the contentSize is also CGRectZero.
Edit: If you don't want to override the creation of the scrollView (because you have already set it in Interface Builder), remove the line _scrlView = [[UIScrollView alloc]init];.
But if you are using Auto Layout in the storyboard you should call [self slider] in viewDidLayoutSubviews.

Answer 2

You need to set frame first, for getting its width and height,
- (void)viewDidLoad {
[super viewDidLoad];
[self slider];
}
-(void)slider{
_scrlView = [[UIScrollView alloc] initWithFrame:CGRectMake(YOUR_X, YOUR_X, YOUR_WIDTH, YOUR_HIEGHT)];
// do this if you have not added Scrollview in storyboard, if Added, then no need to invoke, init by line [[UIScrollView alloc] init] ;
...
...
[self.view addSubview:_scrlView];
}
I would suggest one more thing, to call your slider method from viewDidAppear method of UIView
Enjoy Coding !!

Answer 3

You need to allocate the ScrollView if have not used a storyboard. Also in that case, specify a frame:
_scrlView = [[UIScrollView alloc] initWithFrame:CGRectMake(0,0,self.view.frame.size.width,self.view.frame.size.height)];

Answer 4

You are reallocating the imageviews, try to set image after allocating it once.
Another thing : Dont init scrollview again.
- (void)viewDidLoad {
[super viewDidLoad];
[self slider];
}
-(void)slider{
_scrlView.backgroundColor = [UIColor blackColor];
_scrlView.pagingEnabled = YES;
_scrlView.delegate = self;
_scrlView.showsHorizontalScrollIndicator = false;
_scrlView.layer.cornerRadius = 2;
_scrlView.contentSize = CGSizeMake(_scrlView.frame.size.width * 3, _scrlView.frame.size.height);
_img1 = [[UIImageView alloc] initWithFrame:CGRectMake((_scrlView.frame.size.width*0),0,_scrlView.frame.size.width,_scrlView.frame.size.height)];
_img2 = [[UIImageView alloc] initWithFrame:CGRectMake((_scrlView.frame.size.width*1),0,_scrlView.frame.size.width,_scrlView.frame.size.height)];
_img3 = [[UIImageView alloc] initWithFrame:CGRectMake((_scrlView.frame.size.width*2),0,_scrlView.frame.size.width,_scrlView.frame.size.height)];
[_img1 setImage:[UIImage imageNamed:#"1234.jpg"]];
[_img2 setImage:[UIImage imageNamed:#"1234.jpg"]];
[_img3 setImage:[UIImage imageNamed:#"1234.jpg"]];
[_scrlView addSubview:_img1];
[_scrlView addSubview:_img2];
[_scrlView addSubview:_img3];
}

Answer 5

My reply would be
if you are not using Storyboard or Interface builder , also autolayout is unchecked, set the frame of uiscrollview after its allocation and use alloc init only one time for one image. Add image on scrollview and scrollview on superview
if you are not using Storyboard or Interface builder and autolayout is checked, then put proper constraints on scrollview and imageviews. Read this
https://developer.apple.com/library/ios/technotes/tn2154/_index.html