ios - UIbarbuttonitem出现导致崩溃

Question

CommonViewController，它继承自UINavigationController。我在其中完成了以下方法。

+ (void)initialize{
    UINavigationBar *naVcBar = [UINavigationBar appearance];
    [naVcBar setBackgroundImage:[UIImage imageNamed:@"bg_nav"] forBarMetrics:UIBarMetricsDefault];

    UIBarButtonItem *buttonItem = [UIBarButtonItem appearance];
    NSMutableDictionary *textAttributes = [NSMutableDictionary dictionary];
    [textAttributes setObject:[UIColor blackColor] forKey:UITextAttributeFont];
    [buttonItem setTitleTextAttributes:textAttributes forState:UIControlStateNormal];
}

然后，有一个名为MovieListViewController的viewController，就是那个CommonViewController的rootViewController，下面是里面的代码。

- (void)viewDidLoad {
    [super viewDidLoad];
    UIBarButtonItem *right=[[UIBarButtonItem alloc] initWithTitle:@"切换模式" style:(UIBarButtonItemStylePlain) target:self action:@selector(exchangeView)];
    self.navigationItem.rightBarButtonItem=right;
}

结果就是程序崩溃了。它崩溃于:self.navigationItem.rightBarButtonItem=right;

所以我尝试修复它并发现当我删除代码时

UIBarButtonItem 
*buttonItem = [UIBarButtonItem appearance];
    NSMutableDictionary *textAttributes = [NSMutableDictionary dictionary];
    [textAttributes setObject:[UIColor blackColor] forKey:UITextAttributeFont];
    [buttonItem setTitleTextAttributes:textAttributes forState:UIControlStateNormal];

一切正常。但我不知道原因，为什么？谢谢!

错误:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UICachedDeviceWhiteColor pointSize]: unrecognized selector sent to instance 0x7fb048c3b3d0'

Answer 1

你的问题出在这一行:

[textAttributes setObject:[UIColor blackColor] forKey:UITextAttributeFont];

您传递的是一种颜色，但指定了“字体”属性。改变两者之一。要么传入字体而不是颜色，要么将键更改为用于颜色的键。

此外，UITextAttributeFont 已弃用。请改用 NSFontAttributeName。