创建UIBarButtonItem扩展

本人是作ios的之前一直用oc开发，现在摸索swift 虽然有点晚，用的oc代码转换成swift的可能存在瑕疵。欢迎提出问题一起学习进步。

上代码：

import Foundation

import UIKit

extension UIBarButtonItem{

class public func      itemWithTarget(target:Any?,action:Selector,image:String,highimage:String) ->UIBarButtonItem{

let btn:UIButton = UIButton.init(type: UIButtonType.custom) btn.setBackgroundImage(UIImage.init(named: image), for: UIControlState.normal) btn.setBackgroundImage(UIImage.init(named: highimage), for: UIControlState.highlighted) var rect:CGRect = CGRect.zero

rect.size = (btn.currentBackgroundImage?.size)!

btn.frame = rect btn.addTarget(target, action: action, for: UIControlEvents.touchUpInside) return UIBarButtonItem.init(customView: btn) } }

（在控制器里）调用：（我这边定义的是返回按钮）

viewController.navigationItem.leftBarButtonItem = UIBarButtonItem.itemWithTarget(target: self, action: #selector(back), image:"返回", highimage:"ss")

@objc private func back()

{ self.popToRootViewController(animated: true); }

我写的代码不一定对，但是能运行！