Type 'UIPageViewController.OptionsKey' (aka 'NSString') has no member 'interPageSpacing'

Question

I don't know what's the matter with Xcode. I want to create a UIPageViewController using the initializer in one of my company project:

init(transitionStyle style: UIPageViewController.TransitionStyle,
     navigationOrientation: UIPageViewController.NavigationOrientation, 
     options: [UIPageViewController.OptionsKey : Any]? = nil)

But Xcode keeps giving this error message.

This is my code:

let vc = UIPageViewController(transitionStyle: .scroll, 
                              navigationOrientation: .vertical, 
                              options: [UIPageViewController.OptionsKey.interPageSpacing: 10])

Meanwhile, in new demo project I created just now from the template Page-based App (as bellow), it builds without any error.

How to fix/walkaround it?

Answer 1

The syntax was different in Swift 4. Your current project might be in Swift 4.0. Change its swift version to 4.2 and above. Or use the below code

init(transitionStyle style: UIPageViewControllerTransitionStyle, 
    navigationOrientation: UIPageViewControllerNavigationOrientation, 
    options: [String : Any]? = nil) 

Swift 4.0

let vc = UIPageViewController(transitionStyle: .scroll,
                                      navigationOrientation: .vertical,
                                      options: [UIPageViewControllerOptionInterPageSpacingKey : 10])

Swift 4.2 and above

let vc = UIPageViewController(transitionStyle: .scroll, 
                              navigationOrientation: .vertical, 
                              options: [UIPageViewController.OptionsKey.interPageSpacing : 10])