UIimage not appearing over scrollview in iOS - ios

Question

Need to scroll the scrollview horizontally and with images under it.
It is scrolling horizontally but cannot see my images over it even after the changing the background. Please find the code below :-
#import "ViewController.h"
#interface ViewController () <UIScrollViewDelegate>
#property (nonatomic , weak) IBOutlet UIScrollView *scrollView;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
for(int i=0; i<5; i++) {
UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake((self.view.window.frame.size.width/5)*i, 0, self.view.window.frame.size.width/5, 48)];
imageView.image = [UIImage imageNamed:#"t3"];
imageView.backgroundColor = [UIColor blackColor];
[_scrollView addSubview:imageView];
}
_scrollView.contentSize = CGSizeMake(self.view.window.frame.size.width, 48.0f);
[self.view addSubview:_scrollView];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end

Answer 1

Set a break point in your loop and check the frames of your imageviews and check that you image "t3" is actually being loaded.
Other things you could change,
You don't need to use self.view.window.frame, just use self.view.frame.
You add your scrollview to your view, but it's an IBOutlet, you don't need to do this if you already have it in the hierarchy on the storyboard or xib.
If you still have problems please comment, good luck.

Answer 2

The problem is about self.view.window.
From Apple's document, is says that
This property is nil if the view has not yet been added to a window.
You have not added self.view to a window yet, so if you use
NSLog(#"self.view.window: %#", self.view.window);
the log will be
self.view.window: (null)
That is to say, the value of self.view.window.frame.size.width is 0.
So the solution is easy:
Use self.view.frame.size.width instead of self.view.window.frame.size.width.
OR use the code below to add self.view to a window
[[[[UIApplication sharedApplication] windows] firstObject] addSubview:self.view];