iOS 11 使用两种方法替换(Method Swizzling)去掉导航栏返回按钮的文字

  方法一:设置BarButtonItem的文本样式为透明颜色,代码如下:


[[UIBarButtonItem appearance] setTitleTextAttributes:@{NSForegroundColorAttributeName: [UIColor clearColor]} forState:UIControlStateNormal]; 
[[UIBarButtonItem appearance] setTitleTextAttributes:@{NSForegroundColorAttributeName: [UIColor clearColor]} forState:UIControlStateHighlighted]; 

   此外这种方法会导致title不能居中,被偏移很多,如下所示(虽然不被显示,也占了导航栏左边很大一部分位置)

     方法二:给UIViewController添加类别,然后在load方法里面用Method Swzilling方法替换 交换ViewDidAppear,部分代码如下


+(void)load {
  swizzleMethod([self class], @selector(viewDidAppear:), @selector(ac_viewDidAppear));
}
- (void)ac_viewDidAppear{
  self.navigationItem.backBarButtonItem = [[UIBarButtonItem alloc]
                       initWithTitle:@""
                       style:UIBarButtonItemStylePlain
                       target:self
                       action:nil];
  [self ac_viewDidAppear];
}
void swizzleMethod(Class class, SEL originalSelector, SEL swizzledSelector)
{
  // the method might not exist in the class, but in its superclass
  Method originalMethod = class_getInstanceMethod(class, originalSelector);
  Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
  // class_addMethod will fail if original method already exists
  BOOL didAddMethod = class_addMethod(class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));
  // the method doesn't exist and we just added one
  if (didAddMethod) {
    class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
  }
  else {
    method_exchangeImplementations(originalMethod, swizzledMethod);
  }
}

注意事项:

要给整个backButtonItem赋值才可以,????这种方法不行,因为backBarButtonItem默认为空,给nil方法消息,默认声明都不执行(参考官网

self.navigationItem.backBarButtonItem.title = @" ";

leftBarButtonItem 与backBarButtonItem 的显示关系:

有leftBarButtonItem则优先显示当前VC的leftBarButtonItem,无则显示上个VC的backBarButtonItem,再无则显示上个VC的title(参考官网   还是官网解释的清楚)

总结

以上所述是小编给大家介绍的iOS 11 使用两种方法替换(Method Swizzling)去掉导航栏返回按钮的文字,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。

在此也非常感谢大家对脚本之家网站的支持!

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