iOS11后，系统更改了UINavigationBar的布局结构，所以会导致自定义导航按钮的位置会便的很离谱。现在推荐一个简单方法：
有两种方法：
1、如果是全局通用，则使用扩展，

@implementation UINavigationBar (BDFixSpace)

+(void)load {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Method originalMethodImp = class_getInstanceMethod(self, @selector(layoutSubviews));
        Method destMethodImp = class_getInstanceMethod(self, @selector(bd_layoutSubviews));
        method_exchangeImplementations(originalMethodImp, destMethodImp);
    });
}

-(void)bd_layoutSubviews{
    
    [self bd_layoutSubviews];
    for (UIView *subview in self.subviews) {
        if ([NSStringFromClass([subview class]) containsString:@"_UINavigationBarContentView"]) {
            UIEdgeInsets margins = subview.layoutMargins;
            if(CURRENT_VERSION >= 11.0){
                subview.frame = CGRectMake(-margins.left*0.5, -margins.top, margins.left*0.5 + margins.right*0.5 + subview.frame.size.width, margins.top + margins.bottom + subview.frame.size.height);
            }else{
                margins = UIEdgeInsetsZero;
            }
            break;
        }
    }
}

2、如果是自定义navigationbar,则重写layoutsubview方法即可

-(void)layoutSubviews{
    
    [self layoutSubviews];
    for (UIView *subview in self.subviews) {
        if ([NSStringFromClass([subview class]) containsString:@"_UINavigationBarContentView"]) {
            UIEdgeInsets margins = subview.layoutMargins;
            if(CURRENT_VERSION >= 11.0){
                subview.frame = CGRectMake(-margins.left*0.5, -margins.top, margins.left*0.5 + margins.right*0.5 + subview.frame.size.width, margins.top + margins.bottom + subview.frame.size.height);
            }else{
                margins = UIEdgeInsetsZero;
            }
            break;
        }
    }
}

是不是很简单！
谢谢，如果帮到你还请点个赞哈！