iOS：无法更改UIBarButtonItem的颜色

Question

I basically have a ViewController that is the root ViewController of a UINavigationController. Basically I have a UIBarButtonItem that when a user presses on it, its tint color should toggle between red and green. But the color doesn't seem to change. My code:

@interface TestButtonColorViewController (){
    BOOL colorMode;
}
@end

@implementation TestButtonColorViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    colorMode = NO;

    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Change" style:UIBarButtonItemStyleBordered target:self action:@selector(changeColor)];


}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)changeColor{
    colorMode = !colorMode;

    if (colorMode) {
        [[UIBarButtonItem appearanceWhenContainedIn:[UINavigationBar class], nil] setTintColor:[UIColor redColor]];
    }
    else {
        [[UIBarButtonItem appearanceWhenContainedIn:[UINavigationBar class], nil] setTintColor:[UIColor greenColor]];
    }
}

Answer 1

As CSmith has suggested, you should set the tint directly:

- (void)changeColor {
    colorMode = !colorMode;

    if (colorMode) {
        [self.navigationItem.rightBarButtonItem setTintColor:[UIColor redColor]];
    } else {
        [self.navigationItem.rightBarButtonItem setTintColor:[UIColor greenColor]];
    }
}