How do i remove text from back button on navbar wi

问题:

I set an arrow custom image to navigation bar by adding the following code in app delegate, it works but now im looking to remove the text completely for back button.

UIImage * backButtonImage = [UIImage imageNamed: @"BackButtonGrey.png"];
backButtonImage = [backButtonImage stretchableImageWithLeftCapWidth: 15.0 topCapHeight: 30.0];
[[UIBarButtonItem appearance]  setBackButtonBackgroundImage: backButtonImage  forState: UIControlStateNormal  barMetrics: UIBarMetricsDefault];

回答1:

I just did it like this, worked fine for me :-)

UIImage *backButtonImage = [UIImage imageNamed:@"navigationBarBack.png"];
UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];

[backButton setImage:backButtonImage
            forState:UIControlStateNormal];

backButton.frame = CGRectMake(0, 0, backButtonImage.size.width, backButtonImage.size.height);

[backButton addTarget:self
               action:@selector(popViewController)
     forControlEvents:UIControlEventTouchUpInside];

UIBarButtonItem *backBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];
self.navigationItem.leftBarButtonItem = backBarButtonItem;

回答2:

Simply move the text vertically so far that it no longer appears. This can be done at app launch in your app delegate.

[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, 20.f) forBarMetrics:UIBarMetricsDefault];

Normally this call is for tweaking the vertical text position which can vary depending on the font used. Here the text is moved far enough that it's no longer inside the Back button view, and so is clipped into non-existence.

回答3:

I really don't think is a good practice for a developer to adjust the offset of the text in order to hide it.

A cleaner solution would be to just add to the navigation controller back button a new button where the title is an empty string. You should add this in the previous calling view controller in viewWillAppear (not the current one):

UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:@"" style:UIBarButtonItemStylePlain target:nil action:nil];
self.navigationItem.backBarButtonItem = backButton;

回答4:

[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(-100.f, 0) forBarMetrics:UIBarMetricsDefault];

回答5:

Do not use the appearance proxy. Instead, for every view controller, put this code into its viewDidLoad implementation:

UIImage * backButtonImage = 
    [UIImage imageNamed: @"BackButtonGrey.png"];
backButtonImage = 
    [backButtonImage stretchableImageWithLeftCapWidth: 15.0 topCapHeight: 30.0];

UIBarButtonItem* b =
     [[UIBarButtonItem alloc] 
          initWithImage:backButtonImage
          style:UIBarButtonItemStylePlain target:nil action:nil];
self.navigationItem.backBarButtonItem = b;

That will cause the next view controller pushed onto the navigation stack to have a back button consisting of just the image.

(However, I should point out that stretchableImageWithLeftCapWidth:... is deprecated. You should be using resizableImage....)

回答6:

To set a backbutton text, you set a new backbutton to the current viewController before pushing or presenting then new one which would show the text of the backbutton:

In your current viewController (not the new one which will show the back-button):

vc                                    = [[MyNewViewController alloc]initWith...];
vc.title                              = @"New ViewController";
self.navigationItem.backBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"Back" style:UIBarButtonItemStylePlain target:nil action:nil];
[self.navigationController pushViewController:vc animated:YES];

So if you want to remove the text, just use @"" as a title for the new backbutton.

To set a backbutton-icon for the entire app, use the following code in your appDelegate class. Not every icon fits perfectly, so if you have to move it around a little, you can use the "backInsets". In my example the icon will move 2px down.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    ...
    ...
    [self customBackButtonIcon];
    return YES;
}

- (void)customBackButtonIcon
{        
    UIEdgeInsets backInsets = UIEdgeInsetsMake(0, 0, -2, 0);
    UIImage *backImg = [[[UIImage imageNamed:@"back_button_white"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal] imageWithAlignmentRectInsets:backInsets];
    [[UINavigationBar appearance] setBackIndicatorImage:backImg];
    [[UINavigationBar appearance] setBackIndicatorTransitionMaskImage:backImg];
}

Tested with iOS9

回答7:

UIBarButtonItem *newBackButton =
[[UIBarButtonItem alloc] initWithTitle:@""
                                 style:UIBarButtonItemStylePlain
                                target:nil
                                action:nil];
[[self navigationItem] setBackBarButtonItem:newBackButton];

回答8:

Perfect solution globally

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

    UIBarButtonItem.appearance().setTitleTextAttributes([NSForegroundColorAttributeName:UIColor.clearColor()], forState: UIControlState.Normal)
    UIBarButtonItem.appearance().setTitleTextAttributes([NSForegroundColorAttributeName:UIColor.clearColor()], forState: UIControlState.Highlighted)

    return true
}