UIScrollView behave strange while subview have drawRect method

Description:

we are adding custom UIView(have drawRect) inside the UIScrollView and its content size as more than 5500(width or height) then the UIScrollView behave strangely.
Note: if we remove the drawRect method then it will working fine.

Steps to Reproduce:

1. Run the attached project
2. See the reported issue

Expected Behavior:

- Subview of scroll view, draw method working

Actual Behavior:

- Subview of scroll view, draw method not working

Code Snippet :

- (void)viewDidLoad {

[super viewDidLoad];

//// create scroll view

UIScrollView* scrollView = [[UIScrollView alloc] init];

scrollView.backgroundColor = UIColor.redColor;

scrollView.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);

scrollView.contentSize = CGSizeMake(6000, self.view.frame.size.height);

//// create custom view with drawRect method

CustomView* customView = [[CustomView alloc] initWithFrame:CGRectMake(0, 0, 6000, self.view.frame.size.height)];

//// add views to super view

[self.view addSubview:scrollView];

[scrollView addSubview:customView];

}

CustomView:

- (CustomView*)initWithFrame:(CGRect)frame

{

self = [super initWithFrame:frame];

if(self)

{

self.backgroundColor = UIColor.blueColor;

}

return self;

}

- (void)drawRect:(CGRect)rect

{

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetLineWidth(context, 10);

CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);

CGContextMoveToPoint(context, 0, self.frame.size.height / 2);

CGContextAddLineToPoint(context, self.frame.size.width, self.frame.size.height / 2);

CGContextStrokePath(context);

}

@end

Sample: https://drive.google.com/open?id=1446iyIvd4lax5p4s2TPAf5TEGdNYy3xg

Screen record: https://drive.google.com/open?id=1rxyUhdq66GjTHx_P2p-CYUL7LtqMTRGN