swift 基礎小結02 -- VFL約束、屬性的get和set方法、懶加載、方法替換

1、屬性的get和set方法

    

    一、自定義屬性的set和get方法

    

    private(set) var _image:UIImage?

    //自定義屬性get，set

    var image : UIImage?{

        get{

            return _image

        }

        set(newValue){

            _image = newValue

            self.imageView?.image = _image

        }

    }

    二、重寫父類屬性的set和get方法

 

//重寫父類屬性get，set

    override var tag:Int{

       

        get{

           return super.tag

        }

        set(newValue){

            super.tag = newValue

            self.button?.tag = newValue

        }

    

 

 

2、VFL添加約束

 

    和objective-c中類似，代碼以下

let tabbarHeight:CGFloat = 49.0

func setupBaseUI(){

        self.contentView.translatesAutoresizingMaskIntoConstraints = false

        self.lineView.translatesAutoresizingMaskIntoConstraints = false

        self.tabBar.translatesAutoresizingMaskIntoConstraints = false

        let views = self.ConstraintDictionWithArray(nameArray: [self.contentView,self.lineView,self.tabBar,self.view], object: self);

        NSLayoutConstraint.activate(NSLayoutConstraint.constraints(withVisualFormat: "H:|[contentView]|", options: NSLayoutFormatOptions.alignAllLeft, metrics: nil, views: views))

       

        NSLayoutConstraint.activate(NSLayoutConstraint.constraints(withVisualFormat: "H:|[tabBar]|", options: NSLayoutFormatOptions.alignAllLeft, metrics: nil, views: views))

      

        NSLayoutConstraint.activate(NSLayoutConstraint.constraints(withVisualFormat: "V:|[contentView][tabBar(tabbarHeight)]|", options: NSLayoutFormatOptions.alignAllLeft, metrics: ["tabbarHeight":(self.isIphoneX() ? tabbarHeight_iphoneX : tabbarHeight)], views: views))

      

        NSLayoutConstraint.activate(NSLayoutConstraint.constraints(withVisualFormat: "H:|[lineView]|", options: NSLayoutFormatOptions.alignAllLeft, metrics: nil, views: views))

        NSLayoutConstraint.activate(NSLayoutConstraint.constraints(withVisualFormat: "V:|[lineView(0.5)]", options: NSLayoutFormatOptions.alignAllLeft, metrics: nil, views: views))

    }

 

//MARK: 至關於OC中的NSBinding（由於oc中沒有宏定義，沒有NSBinding這個宏定義，因此寫一個方法代替這個方法）

    func ConstraintDictionWithArray(nameArray:Array<UIView>,object:AnyObject) -> Dictionary<String,AnyObject> {

       

        var dict:Dictionary<String,AnyObject> = [:]

       

        var count:UInt32 = 0

       

        let ivars = class_copyIvarList(object.classForCoder, &count)

       

        for i in 0...Int(count) {

           

            let obj = object_getIvar(object, ivars![i])

           

            if let temp = obj as? UIView {

               

                if nameArray.contains(temp){

                   

                    let name = String.init(cString: ivar_getName(ivars![i])!)

                   

                    dict[name] = temp

                }

               

            }

        }

        free(ivars)

       

        return dict

    }

 

3、懶加載

    

    一、懶加載建立label

    

//MARK: 懶加載建立label

    lazy var lazyLabel: UILabel = self.addLabel_d(title: "");

    func addLabel_d(title:String) -> UILabel {

        let label = UILabel(frame: CGRect.init(x: 0, y: 0, width: 200, height: 40))

        label.center = self.view.center

        label.backgroundColor = UIColor.gray

        label.textColor = UIColor.white

        label.textAlignment = NSTextAlignment.center

        label.numberOfLines = 0

        label.lineBreakMode = NSLineBreakMode.byWordWrapping

        label.text = title

        label.font = UIFont.systemFont(ofSize: 17)

        return label;

    }

    

    二、懶加載數組

//lazy

    lazy var datasource:NSArray = {

       

        var tmpdatasource = NSArray(objects: ["title":"dispatch使用","content":["sync -- 同步","async -- 異步","delay -- 延遲執行三秒","main -- 主線程","global -- 全局併發隊列"]],["title":"網絡請求","content":["GET -- 請求","POST -- 請求","下載圖片"]],["title":"自定義組件","content":["toast","。。。"]])

       

        return tmpdatasource

    }()

 

4、方法替換

 

extension UIViewController{

   

    public class func initializeMethod() {

        let originalSelector = #selector(UIViewController.viewWillAppear(_:))

        let swizzledSelector = #selector(UIViewController.dealWithJF_Tabbar(animated:))

        let originalMethod = class_getInstanceMethod(self, originalSelector)

        let swizzledMethod = class_getInstanceMethod(self, swizzledSelector)

        //在進行 Swizzling 的時候,須要用 class_addMethod 先進行判斷一下原有類中是否有要替換方法的實現

        let didAddMethod: Bool = class_addMethod(self, originalSelector, method_getImplementation(swizzledMethod!), method_getTypeEncoding(swizzledMethod!))

        //若是 class_addMethod 返回 yes,說明當前類中沒有要替換方法的實現,因此須要在父類中查找,這時候就用到 method_getImplemetation 去獲取 class_getInstanceMethod 裏面的方法實現,而後再進行 class_replaceMethod 來實現 Swizzing

        if didAddMethod {

            class_replaceMethod(self, swizzledSelector, method_getImplementation(originalMethod!), method_getTypeEncoding(originalMethod!))

           

        } else {

            method_exchangeImplementations(originalMethod!, swizzledMethod!)

           

        }

       

    }

    @objc func dealWithJF_Tabbar(animated: Bool) {

      

        self.dealWithJF_Tabbar(animated: animated)

         print("處理自定義tabbar隱藏問題")

        self.jf_tabBarController?.tabBar.isHidden = self.jf_hidesBottomBarWhenPushed;

    }

}

 

而後在appdelegate中使用下面方法：

 

    UIViewController.initializeMethod()