Compose UIBarButtonItem changes position slightly

问题:

When presenting a new view with a UIBarButtonSystemItemCompose button in the navigation bar, the position is slightly off and adjusts after the view has come into view.

I think this is a bug in iOS (version 8.3 used). It only happens when using the UIBarButtonSystemItemCompose. It does not happen with other types of Buttons (system, text or custom).

The only code needed to replicate this bug is to use this ViewController code with the view that will come into view:

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

    UIBarButtonItem* composeBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCamera
                                      target:nil
                                      action:nil];

    [self.navigationItem setRightBarButtonItem:composeBarButtonItem animated:YES];
}

@end

I have created a repository on GitHub with bare minimum code to reproduce the problem: https://github.com/jvdvleuten/iOSComposeBarButtonItemBug

Looks related to this: UIBarButtonItems shift position when UINavigationController is presented modally, except my bug only appears when using the UIBarButtonSystemItemCompose.

Any ideas?

回答1:

I used Sergey's answer, but kept an empty space right of my button. I fixed this with a negative spacer, which now works beautifully:

UIBarButtonItem* composeBarButtonItem =
[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCompose
                                              target:nil
                                              action:nil];

UIBarButtonItem *negativeSpacer = [[UIBarButtonItem alloc]
                                       initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace
                                       target:nil action:nil];
negativeSpacer.width = -6;

UIBarButtonItem *dumbBarButtonItem = [UIBarButtonItem new];

self.navigationItem.rightBarButtonItems = @[dumbBarButtonItem, negativeSpacer, self.composeBarButtonItem];

回答2:

This is definitely a bug in iOS 8.0. This 'jump' occurs before viewDidAppear. Here is workaround for this - add another 'dumb'/empty item:

UIBarButtonItem* composeBarButtonItem =
[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCompose
                                              target:nil
                                              action:nil];
UIBarButtonItem *dumbBarButtonItem = [UIBarButtonItem new];
self.navigationItem.rightBarButtonItems = @[dumbBarButtonItem, composeBarButtonItem];

回答3:

A simple workaround:

let composeButton = UIBarButtonItem(image: UIImage(named: "UIButtonBarCompose"), style: .Plain, target: self, action: "compose:")
self.navigationItem.rightBarButtonItem = composeButton

We can get the image 'UIButtonBarCompose' with iOS-Artwork-Extractor.

回答4:

I think this is problem of UIBarButtonSystemItemCompose. need some correction from apple developer team. Untill apple don't get resolve this bug. you can create your custom button and set it to rightBarButtonItem using following code.

UIButton *button =  [UIButton buttonWithType:UIButtonTypeCustom];
    [button setImage:[UIImage imageNamed:@"compose.png"] forState:UIControlStateNormal];
    [button addTarget:self action:@selector(buttonAction:)forControlEvents:UIControlEventTouchUpInside];
    [button setFrame:CGRectMake(0, 0, 53, 31)];

    UIBarButtonItem *barButton = [[UIBarButtonItem alloc] initWithCustomView:button];
    self.navigationItem.rightBarButtonItem = barButton;

-(void)buttonAction:(id)sender{
    NSLog(@"Click");
}

Hope this help you.

回答5:

Nice observation, This problem solved in viewDidAppear. Can you please check this..

- (void)viewDidAppear:(BOOL)animated{    
        [super viewDidAppear:animated];

        UIBarButtonItem* composeBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCompose target:nil action:nil];    
        [self.navigationItem setRightBarButtonItem:composeBarButtonItem animated:YES];    
}

This might help you :)

回答6:

Yes, this is IOS8 bug.

It happens because jumping not a navigation bar item position, its jumping image position inside compose item. This item type seems hasn't override for push animation or something similar, as for example back button.

I think you should create bug on radar and for fix your current trouble, just create custom UIBarButtonItem with the same image.

回答7:

it might happen of animation

try this one. [self.navigationItem setRightBarButtonItem:composeBarButtonItem animated:NO];

hopefully helped :)