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（）

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（  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