如何将这个目标c traitCollection翻译成swift？

Question

我试图将目标C中的代码从这个链接( Sizing class for iPad portrait and Landscape Modes )中翻译出来

下面是我要翻译的代码：

@interface RDTraitCollectionOverrideViewController : UIViewController {
BOOL _willTransitionToPortrait;
UITraitCollection *_traitCollection_CompactRegular;
UITraitCollection *_traitCollection_AnyAny;
}

@end

@implementation RDTraitCollectionOverrideViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self setUpReferenceSizeClasses];
}

- (void)setUpReferenceSizeClasses {
    UITraitCollection *traitCollection_hCompact = [UITraitCollection traitCollectionWithHorizontalSizeClass:UIUserInterfaceSizeClassCompact];
UITraitCollection *traitCollection_vRegular = [UITraitCollection traitCollectionWithVerticalSizeClass:UIUserInterfaceSizeClassRegular];
_traitCollection_CompactRegular = [UITraitCollection traitCollectionWithTraitsFromCollections:@[traitCollection_hCompact, traitCollection_vRegular]];

UITraitCollection *traitCollection_hAny = [UITraitCollection traitCollectionWithHorizontalSizeClass:UIUserInterfaceSizeClassUnspecified];
UITraitCollection *traitCollection_vAny = [UITraitCollection traitCollectionWithVerticalSizeClass:UIUserInterfaceSizeClassUnspecified];
_traitCollection_AnyAny = [UITraitCollection traitCollectionWithTraitsFromCollections:@[traitCollection_hAny, traitCollection_vAny]];
}

-(void)viewWillAppear:(BOOL)animated {
_willTransitionToPortrait = self.view.frame.size.height > self.view.frame.size.width;
}

- (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator {
_willTransitionToPortrait = size.height > size.width;
}

-(UITraitCollection *)overrideTraitCollectionForChildViewController:(UIViewController *)childViewController {
UITraitCollection *traitCollectionForOverride =           (_willTransitionToPortrait) ? _traitCollection_CompactRegular :    _traitCollection_AnyAny;
return traitCollectionForOverride;
}
@end

下面是我所拥有的，请记住，我在类声明下面重命名了一些inital变量：

import UIKit

class ViewController: UIViewController {

var willTransitionToPortrait:Bool = false
var compactRegular = UITraitCollection()
var anyAny = UITraitCollection()

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    setUpReferenceSizeClasses()
}

func setUpReferenceSizeClasses() {

    var traitCollection_hCompact = UITraitCollection(horizontalSizeClass: UIUserInterfaceSizeClass.Compact)
    var traitCollection_vRegular = UITraitCollection(verticalSizeClass: UIUserInterfaceSizeClass.Regular)
    compactRegular = UITraitCollection(traitsFromCollections: [traitCollection_hCompact, traitCollection_vRegular])

    var traitCollection_hAny = UITraitCollection(horizontalSizeClass: UIUserInterfaceSizeClass.Unspecified)
    var traitCollection_vAny = UITraitCollection(verticalSizeClass: UIUserInterfaceSizeClass.Unspecified)
    anyAny = UITraitCollection(traitsFromCollections: [traitCollection_hAny, traitCollection_vAny])
}

override func viewWillAppear(animated: Bool) {

    willTransitionToPortrait = self.view.frame.size.height > self.view.frame.size.width
}

override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) {

    willTransitionToPortrait = size.height > size.width
}


func overrideTraitCollectionForChildViewController(UIViewController) -> childViewController {

    var traitCollectionForOverride = (willTransitionToPortrait) ? compactRegular : anyAny

    return traitCollectionForOverride;
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

我想我几乎都有了，除了最后一个函数，我不知道它是什么意思。任何帮助都将不胜感激。

Answer 1

我认为您在最后一个函数中缺少了“覆盖”，尝试用下面的代码替换：

override func overrideTraitCollectionForChildViewController(childViewController: UIViewController) -> UITraitCollection! {
    //
}

以下是完整的代码：

​

import UIKit

class ViewController: UIViewController {
    
    var willTransitionToPortrait:Bool = false
    var compactRegular = UITraitCollection()
    var anyAny = UITraitCollection()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        setUpReferenceSizeClasses()
    }
    
    func setUpReferenceSizeClasses() {
        
        var traitCollection_hCompact = UITraitCollection(horizontalSizeClass: UIUserInterfaceSizeClass.Compact)
        var traitCollection_vRegular = UITraitCollection(verticalSizeClass: UIUserInterfaceSizeClass.Regular)
        compactRegular = UITraitCollection(traitsFromCollections: [traitCollection_hCompact, traitCollection_vRegular])
        
        var traitCollection_hAny = UITraitCollection(horizontalSizeClass: UIUserInterfaceSizeClass.Unspecified)
        var traitCollection_vAny = UITraitCollection(verticalSizeClass: UIUserInterfaceSizeClass.Unspecified)
        anyAny = UITraitCollection(traitsFromCollections: [traitCollection_hAny, traitCollection_vAny])
    }
    
    override func viewWillAppear(animated: Bool) {
        
        willTransitionToPortrait = self.view.frame.size.height > self.view.frame.size.width
    }
    
    override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) {
        
        willTransitionToPortrait = size.height > size.width
    }
    
    override func overrideTraitCollectionForChildViewController(childViewController: UIViewController) -> UITraitCollection! {
    //
        var traitCollectionForOverride = (willTransitionToPortrait) ? compactRegular : anyAny
        
        return traitCollectionForOverride;
    }
    
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

​