动画没有动画在Swift 3 Xcode 8.1中

Question

当我使用以下代码运行我的应用程序时，它只显示第一帧，而不是循环其他图像。

class ViewController: UIViewController, UITextFieldDelegate {

    var signUpMode = true
    var activityIndicator = UIActivityIndicatorView()


    @IBOutlet weak var emailText: UITextField!
    @IBOutlet weak var passwordText: UITextField!
    @IBOutlet weak var signIn: UIImageView!

    //Animated sign in
    var counter = 0

    var animationStart = false

    var timer = Timer()

    func animateSignIn() {

        signIn.image = UIImage(named: "frame_\(counter)_delay-0.04s.gif")

        counter += 1

        if counter == 128 {

            counter = 0

        }
    }

    func animation (){

        if animationStart == true {

            timer = Timer.scheduledTimer(timeInterval: 0.04, target: self, selector: #selector(ViewController.animateSignIn), userInfo: nil, repeats: true)
        }
    }

然后我将animationStart设置为true ：

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    //remove root view controller navigation bar
    self.navigationController?.navigationBar.isHidden = true
    animationStart = true
}

Answer 1

你在哪里调用函数animation() ？

我认为viewDidLoad应该是这样的

override func viewDidLoad() {
    super.viewDidLoad()
    //remove root view controller navigation bar
    self.navigationController?.navigationBar.isHidden = true
    animationStart = true
    animation() //call animation
}