首先來看三張圖：

程式碼已貼出在圖片下方

無文字返回按鈕設定：

[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60) forBarMetrics:UIBarMetricsDefault];

swift

UIBarButtonItem.appearance().setBackButtonTitlePositionAdjustment(UIOffset(horizontal: 0, vertical: -60), for: UIBarMetrics.default
 
)

自定義返回按鈕（位置與系統位置一致） 為UIViewController新增extension方法，方便呼叫

extension UIViewController{
    // xzCustomBackBarButtonItem
    func customBackBarButtonItem(target:AnyObject?,action:Selector?){

        var action1 = action
        if action1 == nil {
           action1 = #selector(self.navigationController?.popViewController(animated:))
 

        }
        var target1 = target
        if target1 == nil {
            target1 = self.navigationController
        }
        let backBarButtonItem = UIBarButtonItem.init(image: UIImage.init(named: "new-sys-jiantou"), style: UIBarButtonItemStyle.plain, target: target1, action: action1)
//UIImage.init(named: "new-sys-jiantou")  UI提供返回圖片
 


let fixBarButtonItem = UIBarButtonItem.init(barButtonSystemItem: UIBarButtonSystemItem.fixedSpace, target: nil, action: nil)
        fixBarButtonItem.width = -10
        self.navigationItem.leftBarButtonItems = [fixBarButtonItem,backBarButtonItem]
    }
}