我如何自定义导航返回按钮在iOS 7及以上没有标题?(即只使用箭头)

self.navigationItem.leftBarButtonItem = self.editButtonItem;

我只是想知道它们是否有self。backbuttonitem;

OR

像这样的东西?

self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]
                   initWithBarButtonSystemItem:UIBarButtonSystemItemBACK 
                   target:self action:@selector(back)];

当前回答

所有的答案都不能解决问题。在每个视图控制器中设置后退按钮标题,并且添加偏移量仍然会使下一个视图控制器标题向右移动,这是不可接受的。

这里是使用方法swizzling的方法,只需创建新的扩展UINavigationItem

import UIKit

extension UINavigationItem {
    public override class func initialize() {

    struct Static {
        static var token: dispatch_once_t = 0
    }

    // make sure this isn't a subclass
    if self !== UINavigationItem.self {
        return
    }

    dispatch_once(&Static.token) {
        let originalSelector = Selector("backBarButtonItem")
        let swizzledSelector = #selector(UINavigationItem.noTitleBackBarButtonItem)

        let originalMethod = class_getInstanceMethod(self, originalSelector)
        let swizzledMethod = class_getInstanceMethod(self, swizzledSelector)

        let didAddMethod = class_addMethod(self, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod))

        if didAddMethod {
            class_replaceMethod(self, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod))
        } else {
            method_exchangeImplementations(originalMethod, swizzledMethod)
        }
    }
}

// MARK: - Method Swizzling

struct AssociatedKeys {
    static var ArrowBackButtonKey = "noTitleArrowBackButtonKey"
}

func noTitleBackBarButtonItem() -> UIBarButtonItem? {
    if let item = self.noTitleBackBarButtonItem() {
        return item
    }

    if let item = objc_getAssociatedObject(self, &AssociatedKeys.ArrowBackButtonKey) as? UIBarButtonItem {
        return item
    } else {
        let newItem = UIBarButtonItem(title: " ", style: UIBarButtonItemStyle.Plain, target: nil, action: nil)
        objc_setAssociatedObject(self, &AssociatedKeys.ArrowBackButtonKey, newItem as UIBarButtonItem?, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
        return newItem
    }
}
}

其他回答

其实很简单,我是这么做的:

Objective - C

// Set this in every view controller so that the back button displays back instead of the root view controller name
self.navigationItem.backBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"" style:UIBarButtonItemStylePlain target:nil action:nil];

斯威夫特2

self.navigationItem.backBarButtonItem = UIBarButtonItem(title: "", style: .Plain, target: nil, action: nil)

斯威夫特3

self.navigationItem.backBarButtonItem = UIBarButtonItem(title: "", style: .plain, target: nil, action: nil)

把这一行放到推送到堆栈(前一个视图控制器)的视图控制器中。新按下的视图控制器返回按钮现在将显示你为initWithTitle所放的任何东西,在本例中是一个空字符串。

这就是我怎么做的,也是最简单,最有效,最清晰的方法。

如果嵌入在导航控制器上,这是有效的

斯威夫特3

在viewDidLoad中,我把这个添加到视图控制器中,你想让后退按钮只是箭头。

if let topItem = self.navigationController?.navigationBar.topItem {
   topItem.backBarButtonItem = UIBarButtonItem(title: "", style: .plain, target: nil, action: nil)
}

这个和@Kyle Begeman的回答的不同之处在于你在视图控制器上调用这个你想让后退按钮只是箭头,而不是在push stack视图控制器上。

我写了一个扩展,使这更容易:

extension UIViewController {

    /// Convenience for setting the back button, which will be used on any view controller that this one pushes onto the stack
    @objc var backButtonTitle: String? {
        get {
            return navigationItem.backBarButtonItem?.title
        }
        set {
            if let existingBackBarButtonItem = navigationItem.backBarButtonItem {
                existingBackBarButtonItem.title = newValue
            }
            else {
                let newNavigationItem = UIBarButtonItem(title: newValue, style:.plain, target: nil, action: nil)
                navigationItem.backBarButtonItem = newNavigationItem
            }
        }
    }

}

在你的第一个ViewController的prepareForSegue:方法中,你设置视图标题为@"",所以当下一个视图被推送时,它将显示前一个ViewController标题为@""。

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
    self.navigationItem.title = @" ";
}

唯一的问题是,当你点击返回按钮时,你之前的视图将没有标题,所以你可以在viewWillAppear上再次添加它:

-(void)viewWillAppear:(BOOL)animated{
   self.navigationItem.title = @"First View Title";
}

我不太喜欢这个解决方案,但它是可行的,我没有找到其他方法来做到这一点。

你可以子类化UINavigationController,将自己设置为委托,并在委托方法navigationController:willShowViewController:animated中设置backBarButtonItem:

@interface Custom_NavigationController : UINavigationController <UINavigationControllerDelegate>

@end

@implementation Custom_NavigationController

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.delegate = self;
}

#pragma mark - UINavigationControllerDelegate

- (void)navigationController:(UINavigationController *)navigationController     willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    viewController.navigationItem.backBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"" style:UIBarButtonItemStylePlain target:nil action:nil];
}

@end