UITraitCollection -迅速到达目标-C

Question

我正试图把斯威夫特转变成目标-C。下面是我的代码：

Swift

import UIKit

protocol TraitCollectionOverridable {
    func preferredTraitCollection() -> UITraitCollection?
}

class CustomNavigationController: UINavigationController {
    override func overrideTraitCollectionForChildViewController(childViewController: UIViewController) -> UITraitCollection? {
        guard let conformingViewController = childViewController as? TraitCollectionOverridable else {
            return super.overrideTraitCollectionForChildViewController(childViewController)
        }

        return conformingViewController.preferredTraitCollection()
    }
}

目标-C头文件

@protocol TraitCollectionOverridable <NSObject>
- (UITraitCollection *) preferredTraitCollection;
@end

@interface CustomNavigationController : UINavigationController
@property (nonatomic, weak) id <TraitCollectionOverridable> traitsDelegate;
@end

.m文件

@implementation CustomNavigationController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.traitsDelegate preferredTraitCollection];
    // Do any additional setup after loading the view.
}


- (UITraitCollection *)overrideTraitCollectionForChildViewController:(UIViewController *)childViewController
{
    if (CGRectGetWidth(self.view.bounds) < CGRectGetHeight(self.view.bounds)) {
        return [UITraitCollection traitCollectionWithHorizontalSizeClass:UIUserInterfaceSizeClassCompact];
    } else {
        return [UITraitCollection traitCollectionWithHorizontalSizeClass:UIUserInterfaceSizeClassRegular];
    }
}

@end

我猜overrideTraitCollectionForChildViewController不是正确转换的。在这方面任何帮助都会很好。

Answer 1

我猜overrideTraitCollectionForChildViewController不是正确转换的。

Obj-C & Swift版本的overrideTraitCollectionForChildViewController并不等价。以下是修正后的代码：

Obj

- (UITraitCollection *)overrideTraitCollectionForChildViewController:(UIViewController *)childViewController
{
    if( [childViewController conformsToProtocol:@protocol(TraitCollectionOverridable)] ) {
        return [(NSObject<TraitCollectionOverridable>*)childViewController preferredTraitCollection];
    } else {
        return [super overrideTraitCollectionForChildViewController:childViewController];
    }
}

斯威夫特

override func overrideTraitCollectionForChildViewController(childViewController: UIViewController) -> UITraitCollection? {
    guard let conformingViewController = childViewController as? TraitCollectionOverridable else {
        return super.overrideTraitCollectionForChildViewController(childViewController)
    }

    return conformingViewController.preferredTraitCollection()
}