Question

没有动画，我正在学习核心动画

运行此代码时，屏幕上不显示while (fgets((char *) sampleText, 3000, fp) != NULL) { for(int i = 0; sampleText[i]; i++) { int temp; temp = utf8_to_codepoint(&sampleText[i], &lenptr); printf("%d\n", temp); printf("i: %d\n", i); for(int k = 0; k < unicodeData[0].languagecount; k++) { if(temp <= unicodeData[k].max && temp >= unicodeData[k].min) { unicodeData[k].numChars++; } } } }图像。然后4秒钟后，它重新出现并按预期完成。不知道为什么。我想要的是，当应用程序启动时，top图像会出现在屏幕上，然后在4秒后，top图像向上移动并离开屏幕。

top

有什么想法吗？

Answer 1

所以你希望图像在开始时在屏幕上显示，然后在4秒后从顶部飞起来？您可以通过将动画分组在一起来实现此目的

override func viewDidAppear(animated: Bool)
{
    super.viewDidAppear(animated)

    // keep a track of where we want it to be
    let y = self.top.layer.position.y

    // move it out of the way - this where it will end up after the animation
    self.top.layer.position.y = -self.view.bounds.size.height

    // do nothing, other than display the image for 4 seconds
    let doNothing = CABasicAnimation(keyPath: "position.y")
    doNothing.fromValue = y
    doNothing.toValue = y
    doNothing.duration = 4.0

    // zip it away
    let openTop = CABasicAnimation(keyPath: "position.y")
    openTop.fromValue = y
    openTop.toValue = -self.view.bounds.size.height
    openTop.duration = 1.0
    openTop.beginTime = doNothing.beginTime + doNothing.duration

    // create the group
    let group = CAAnimationGroup()
    group.duration = 5.01
    group.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
    group.removedOnCompletion = false
    group.fillMode = kCAFillModeForwards
    group.animations = [doNothing, openTop]

    self.top.layer.addAnimation(group, forKey: nil)
}

Answer 2

这是我想出的：

let l = top.layer!
let startingPosition = l.position
l.position = CGPointMake( CGRectGetMidX( self.view.bounds ), -l.frame.height * 0.5 )

l.addAnimation({
    let anim = CABasicAnimation( keyPath: "position" )
    anim.fromValue = NSValue( CGPoint:startingPosition )
    anim.beginTime = CACurrentMediaTime() + 4.0
    anim.fillMode = kCAFillModeBoth
    return anim
}(), forKey: nil)

基本核心动画 - 动态图像

2 个答案: