导航条按钮的间距问题

需求：自定义导航条右边按钮的间距

问题：系统导航条rightBarButtonItem默认与右边有30*UI_RATE的间距(UI_RATE是适配比率)

解决如下：封装一个方法

+ (NSArray *)initRightBarButtonItemsWithTarget:(id)target action:(SEL)action title:(NSString *)title font:(CGFloat)font titleColorNormal:(UIColor *)titleColorNormal titleColorHightLight:(UIColor *)titleColorHightLight
{
    UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button addTarget:target action:action forControlEvents:UIControlEventTouchUpInside];
    [button setTitle:title forState:UIControlStateNormal];
    
    button.titleLabel.font = [UIFont systemFontOfSize:fontSize];
    
    if(titleColorNormal){
      [button setTitleColor:titleColorNormal forState:UIControlStateNormal];
    }
    if(titleColorHightLight){
      [button setTitleColor:titleColorHightLight forState:UIControlStateNormal];
    }
    //设置按钮的frame
     /*
      *[NSString calculateTextWidth:title font:[UIFont systemFontOfSize:fontSize]]是计算文章的宽度
      *48*UI_RATE是自定义的间距，因为文字是居中的，所以左右间距是24*UI_RATE
      */
    [button setFrame:CGRectMake(0, 0,48 * UI_RATE + [NSString calculateTextWidth:title font:[UIFont systemFontOfSize:fontSize]], 40)];
    
    //添加一个占位UIBarButtonItem来代替那30 * UI_RATE的留白间距
    UIBarButtonItem * negativeSpacer = [[ UIBarButtonItem alloc ] initWithBarButtonSystemItem : UIBarButtonSystemItemFixedSpace target:nil action:nil];
    //设置width为-30 * UI_RATE相当于往右偏移-30 * UI_RATE
    negativeSpacer.width = -30 * UI_RATE;
    UIBarButtonItem * buttonItem = [[UIBarButtonItem alloc] initWithCustomView:button];
    //顺序不能换（rightBarButtonItems界面的展示是从最右边从第一个依次向左摆放）
    return @[negativeSpacer,buttonItem];
}

self.navigationItem.rightBarButtonItems = [UIBarButtonItem initRightBarButtonItemsWithTarget:self action:@selector(sureAction:) title:@"确定" font:0 titleColorNormal:nil titleColorHightLight:nil];

导航条左边leftBarButtonItems同理:leftBarButtonItems界面的展示是从最左边边从第一个依次向右摆放