[功能]按下按鈕並變換按鈕圖片

//宣告一個按鈕

@IBOutletweakvar clickButtonImage: UIButton!

//宣告一個按鈕動作

 @IBAction func clickButton(sender: AnyObject) {

//當點下去選擇後,變成反選擇,同樣的反選擇點下去後變成選擇
        clickButtonImage.selected = !clickButtonImage.selected

//執行store_select這個function
        store_select()
    }

//設置store_select這個function

func store_select(){
     
//設置沒選擇時的圖片與被選擇後的圖片      clickButtonImage.setImage(UIImage(named:"ui__fc_n_plus"),forState:UIControlState.Normal)
        clickButtonImage.setImage(UIImage(named:"ui__fc_n_minus"),forState:UIControlState.Selected)

    }