iOS11之后導航欄默認層級發(fā)生改變,自定義的左右view默認放在了_UIButtonBarStackView里面,而左邊的UIButtonBarStackView默認距離導航欄左邊20間距，右邊的UIButtonBarStackView默認距離導航欄右邊20間距，所以可以遍歷找到這個約束修改為0，便能取消間隔。

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還有一種方案是把自定義的按鈕放在一個父View里，讓View整體想左（或向右）便宜，iOS默認可以顯示超出父視圖的部分，但是默認超出父視圖的部分不能響應事件，所以點擊超出部分沒有反應，不推薦這種做法

iOS11之前是直接把自定義的視圖放在了UINavigationBar上, 層級如下圖：
可以通過創(chuàng)建占位空間（UIBarButtonItem(barButtonSystemItem: .fixedSpace, target: nil, action: nil)）來調(diào)整位置

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import UIKit

class NavigationController: UINavigationController, UIGestureRecognizerDelegate {
    
    override func viewDidLoad() {
        super.viewDidLoad()

        // 設置半透明
        self.navigationBar.isTranslucent = true
        
        // navigationBar背景顏色
        self.navigationBar.barTintColor = UIColor.white
        
        // 左右按鈕文本
        self.navigationBar.tintColor = UIColor.rgb(51, 51, 51)
        
        // 標題文本
        self.navigationBar.titleTextAttributes = [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 18),
                                                  NSAttributedString.Key.foregroundColor: UIColor.rgb(51, 51, 51)]
        
        // 返回手勢可用
        self.interactivePopGestureRecognizer?.isEnabled = true
        self.interactivePopGestureRecognizer?.delegate = self
        
        // 背景
//        self.navigationBar.setBackgroundImage(UIImage(), for: .default)
        
        // 隱藏navigationBar分割線
        self.navigationBar.shadowImage = UIImage()
        
//        self.navigationBar.isHidden = true

    }
    
    override func pushViewController(_ viewController: UIViewController, animated: Bool) {
        
        if self.viewControllers.count > 0 {
            viewController.hidesBottomBarWhenPushed = true
            // 替換系統(tǒng)返回鍵
            viewController.addNavigationBarLeftView(self.customLeftBackButton())
        }
        super.pushViewController(viewController, animated: animated)
    }
    
    // 跟控制器不響應返回手勢
    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
        return self.viewControllers.count > 1
    }
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        
        // ios11調(diào)整navigationBar上按鈕的左右間距,默認左右各20
        self.adjustNavigationBarItemsSpacing()
    }
    
    /// 自定義返回按鈕
    private func customLeftBackButton() -> UIButton {
        let backBtn = UIButton(frame: CGRect(x: 0, y: 0, width: 100, height: 44))
        let image = UIImage(named: "navigaitonbar_back_btn_normal")
        backBtn.setImage(image, for: .normal)
        backBtn.imageView?.contentMode = .scaleAspectFit
        backBtn.imageEdgeInsets = UIEdgeInsets(top: 0, left: -60, bottom: 0, right: 0)
        backBtn.addTarget(self, action: #selector(backBtnClicked), for: .touchUpInside)
        return backBtn
        
    }
    
    @objc private func backBtnClicked() {
        self.popViewController(animated: true)
    }
    
    /// ios11調(diào)整navigationBar上按鈕的左右間距,默認左右各20
    private func adjustNavigationBarItemsSpacing() {
        if #available(iOS 11, *) {
            for subview in self.navigationBar.subviews {
                if subview.className.contains("UINavigationBarContentView"){
                    for constant in subview.constraints {
                        if constant.constant == 20 || constant.constant == -20 {
                            constant.constant = 0                    }
                    }
                }
            }
        }
    }
    
}

extension UIViewController {
    
    /// 給系統(tǒng)導航欄添加左邊View(刪除左邊20間隔)
    ///
    /// - Parameter leftView: leftView
    func addNavigationBarLeftView(_ leftView: UIView) {
        let leftItem = UIBarButtonItem(customView: leftView)
        if #available(iOS 11, *) {
            self.navigationItem.leftBarButtonItems = [leftItem]
        } else {
            // 用于消除左邊空隙，要不然按鈕頂不到最左邊
            let leftSpace = UIBarButtonItem(barButtonSystemItem: .fixedSpace, target: nil, action: nil)
            leftSpace.width = -20
            self.navigationItem.leftBarButtonItems = [leftSpace, leftItem]
        }
    }
    
    /// 給系統(tǒng)導航欄添加右邊View(刪除右邊20間隔)
    ///
    /// - Parameter rightView: rightView
    func addNavigationBarRightView(_ rightView: UIView) {
        let rightItem = UIBarButtonItem(customView: rightView)
        if #available(iOS 11, *) {
            self.navigationItem.rightBarButtonItems = [rightItem]
        } else {
            // 用于消除右邊空隙，要不然按鈕頂不到最右邊
            let rightSpace = UIBarButtonItem(barButtonSystemItem: .fixedSpace, target: nil, action: nil)
            rightSpace.width = -20
            self.navigationItem.rightBarButtonItems = [rightSpace, rightItem]
        }
    }
}