Question

我想在for循环中移动一个矩形来创建随机游走。但我只能在最终位置之间不动。我需要做些什么才能看到各个步骤？

import UIKit
import PlaygroundSupport

class ViewController:UIViewController{
    override func viewDidLoad() {
        super.viewDidLoad()
    }
}

class bird: UIView {
    var x:CGFloat
    var y:CGFloat

    override init(frame: CGRect){
        self.x=0
        self.y=0
        super.init(frame: frame)
    }

    func stepit(dx: CGFloat, dy: CGFloat ){
        self.frame.origin.x += dx
        self.frame.origin.y += dy
    }

    override func draw(_ rect: CGRect) {
        self.backgroundColor = #colorLiteral(red: 0.960784316062927, green: 0.705882370471954, blue: 0.200000002980232, alpha: 1.0)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

let viewController = ViewController()
PlaygroundPage.current.liveView = viewController
PlaygroundPage.current.needsIndefiniteExecution = true

let b=bird(frame: CGRect(x: 0, y: 0, width: 20, height: 20))
viewController.view.addSubview(b)

for i in i... 100 {
   b.stepit(dx: CGFloat(arc4random_uniform(10)), dy: CGFloat(arc4random_uniform(10) ))
}

Answer 1

您应该使用animateWithDuration()。将以下代码放在stepit()函数中。正如holex所说，请对该语言进行一些研究。 for循环不会在每一步都暂停，你正在移动鸟，但是你只是看到了结束点，因为它如此快地击中了for循环。

UIView.animateWithDuration(0.5, delay: 0, options: UIViewAnimationOptions.TransitionNone, animations: { () -> Void in

    self.frame.origin.x = dx
    self.frame.origin.y = dy

    }, completion: { (finished: Bool) -> Void in
})

https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIView_Class/

如何使用for循环动画UIView？

1 个答案: