UI的调度信号量

Question

我想让uiviews的alpha动画化，但我似乎做不到。它的行为怪异，并表示错误的运行UI更改不推荐在后台线程上运行，但我不知道如何使它运行在主线程上。谁能帮帮我吗？我相信它跳过了第一个uiview.animate块，并在没有任何动画的情况下执行第二个块中的内容。

函数animateSemaphore（）{

circleRed.alpha = 0.2
circleOrange.alpha = 0.2
circleGreen.alpha = 1

let dispatchSemaphore = DispatchSemaphore(value: 0)
let dispatchQueue = DispatchQueue.global(qos: .background)

dispatchQueue.async {
    UIView.animate(withDuration: 0.5, delay: 5, options: .curveEaseInOut) {
        self.circleOrange.alpha = 1
        self.circleGreen.alpha = 0.2
    } completion: { (_) in
        print("1")
        dispatchSemaphore.signal()
    }
    
    dispatchSemaphore.wait()
    UIView.animate(withDuration: 0.5, delay: 3, options: .curveEaseInOut) {
        self.circleOrange.alpha = 0.2
        self.circleRed.alpha = 1
    } completion: { (_) in
        dispatchSemaphore.signal()
    }
    
    dispatchSemaphore.wait()
    UIView.animate(withDuration: 0.5, delay: 5, options: .curveEaseInOut) {
        self.circleOrange.alpha = 1
    } completion: { (_) in
        dispatchSemaphore.signal()
    }
    
    dispatchSemaphore.wait()
    UIView.animate(withDuration: 0.5, delay: 1, options: .curveEaseInOut) {
        self.circleOrange.alpha = 0.2
        self.circleRed.alpha = 0.2
        self.circleGreen.alpha = 1
    } completion: { (_) in
        self.animateSemaphore()
    }
}

}

Answer 1

您需要在主线程中插入任何与UI/Animate相关的代码，而不是在后台队列中

func animateSemaphore() {
    circleRed.alpha = 0.2
    circleOrange.alpha = 0.2
    circleGreen.alpha = 1
        
    UIView.animate(withDuration: 0.5, delay: 5, options: .curveEaseInOut) {
        self.circleOrange.alpha = 1
        self.circleGreen.alpha = 0.2
    } completion: { (_) in
        UIView.animate(withDuration: 0.5, delay: 3, options: .curveEaseInOut) {
            self.circleOrange.alpha = 0.2
            self.circleRed.alpha = 1
        } completion: { (_) in
            UIView.animate(withDuration: 0.5, delay: 5, options: .curveEaseInOut) {
                self.circleOrange.alpha = 1
            } completion: { (_) in
                UIView.animate(withDuration: 0.5, delay: 1, options: .curveEaseInOut) {
                    self.circleOrange.alpha = 0.2
                    self.circleRed.alpha = 0.2
                    self.circleGreen.alpha = 1
                } completion: { (_) in 
                }
            }
        }
    }
 }

或者玩延迟而不是嵌套动画

func animateSemaphore() {

    circleRed.alpha = 0.2
    circleOrange.alpha = 0.2
    circleGreen.alpha = 1

    UIView.animate(withDuration: 0.5, delay: 5, options: .curveEaseInOut) {
        self.circleOrange.alpha = 1
        self.circleGreen.alpha = 0.2
    } completion: { (_) in
        print("1")
      
    }
    
   
    UIView.animate(withDuration: 0.5, delay: 8.5, options: .curveEaseInOut) {
        self.circleOrange.alpha = 0.2
        self.circleRed.alpha = 1
    } completion: { (_) in
        
    }
    
   
    UIView.animate(withDuration: 0.5, delay: 14, options: .curveEaseInOut) {
        self.circleOrange.alpha = 1
    } completion: { (_) in
       
    }
    
  
    UIView.animate(withDuration: 0.5, delay: 15.5, options: .curveEaseInOut) {
        self.circleOrange.alpha = 0.2
        self.circleRed.alpha = 0.2
        self.circleGreen.alpha = 1
    } completion: { (_) in
        
    }
}