Question

swift按钮点击后出错

代码没提示错误，点击按钮后程序崩溃，但不知道问题出在哪里，求大神解答。

import UIKit

class ViewController: UIViewController {

override func
viewDidLoad() {
super.viewDidLoad()
var playScore:UILabel
var buy:UIButton
var score:Int
= 1000

playScore = UILabel()
playScore.text = String(score)
playScore.frame = CGRectMake(100,100,100,20)

self.view.addSubview(playScore)

buy = UIButton()
buy.frame = CGRectMake(100,150,100,20)

buy.backgroundColor = UIColor.blackColor()
buy.setTitle("buyAdd", forState: UIControlState.Normal)
buy.addTarget(self, action: Selector.convertFromExtendedGraphemeClusterLiteral("buyAdd"), forControlEvents: UIControlEvents.TouchUpInside)
self.view.addSubview(buy)

func buyAdd(){
score = score +
100
playScore.text = String(score)
}
// Do any
additional setup after loading the view, typically from a nib.

}

override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
//
Dispose of any resources that can be recreated.

}

}

Answer 1

我就说一点，你仔细看看func buyAdd()方法是由self调用，你写到viewDidLoad里肯定运行时viewController是找不到该方法的，肯定要报错的。

追问

方法在下方申明了啊，求标准答案

追答

buy.addTarget(self, action: Selector.convertFromExtendedGraphemeClusterLiteral("buyAdd"), forControlEvents: UIControlEvents.TouchUpInside)

buyAdd这个方法是由self来调用的，而你把该方法的定义写到viewDidLoad里，就成了作用域只在viewDidLoad里生效，所以运行时，self要调用buyAdd是找不到该方法的，不知道你懂没。