问题描述
我遇到了一个问题,我的带有 UIView
的 Lottie-Animation
没有正确显示。我使用了很多 dispatch.main.async
,我很确定这会把一切搞砸。
1. 用户点击 Button
并立即显示我的 UIVIew
("coverView")+ Animation
("loadingAnimation")(调用setupLoadingAnimation
)
我必须如何以及在何处调用 animation.play()
和 view.isHidden = false
以便在点击 button
后立即显示?
这是我的结构:
@objc func addWishButtonTapped() {
print("tapped 1")
dispatchQueue.main.async { [weak self] in
guard let self = self else { return }
// ...
self.setUpLoadingAnimation()
// ...
print("tapped 2")
self.crawlWebsite {
print("tapped 3")
self.hideLoadingView()
print("tapped 4")
}
}
}
视图没有被设置,它在 printing
之后停止 print("tapped 2")
并且只打印 print(tapped 3")
。那就是 view
+ loadingAnimatino
变得可见的时候。
Setup Loading Animation:
//MARK: setupLoadingAnimation
func setUpLoadingAnimation(){
dispatchQueue.main.async { [weak self] in
guard let self = self else { return }
self.view.addSubview(self.coverView)
self.coverView.topAnchor.constraint(equalTo: self.wishView.topAnchor).isActive = true
self.coverView.leadingAnchor.constraint(equalTo: self.wishView.leadingAnchor).isActive = true
self.coverView.trailingAnchor.constraint(equalTo: self.wishView.trailingAnchor).isActive = true
self.coverView.bottomAnchor.constraint(equalTo: self.wishView.bottomAnchor).isActive = true
self.loadingAnimation.contentMode = .scaleAspectFit
self.loadingAnimation.translatesAutoresizingMaskIntoConstraints = false
self.coverView.addSubview(self.loadingAnimation)
self.loadingAnimation.centerXAnchor.constraint(equalTo: self.coverView.centerXAnchor).isActive = true
self.loadingAnimation.centerYAnchor.constraint(equalTo: self.coverView.centerYAnchor).isActive = true
self.loadingAnimation.heightAnchor.constraint(equalToConstant: 100).isActive = true
self.loadingAnimation.widthAnchor.constraint(equalToConstant: 100).isActive = true
self.loadingAnimation.loopMode = .loop
self.loadingAnimation.play()
}
}
crawlWebsite:
//MARK: crawlWebsite
func crawlWebsite(finished: @escaping () -> Void){
var html: String?
guard let url = self.url else { return }
let directoryURL = url as NSURL
let urlString: String = directoryURL.absoluteString!
// save url to wish
self.wishView.link = urlString
dispatchQueue.main.async { [weak self] in
guard let self = self else { finished(); return }
html = self.getHTMLfromURL(url: url)
self.getContentFromHTML(html: html,url: url)
self.getopenGraphData(urlString: urlString) {
finished()
}
}
}
我知道这很乱,所以我希望一切都清楚!如果您有任何问题,请告诉我!我很卡在这里...
解决方法
似乎有多余的 DispatchQueue.main.async
调用
- 最好将所有函数中的
DispatchQueue.main.async
移除,并在DispatchQueue.main.async
中的addWishButtonTapped()
中调用所有这些函数
您可以尝试进行以下更改:
@objc func addWishButtonTapped() {
print("tapped 1")
DispatchQueue.main.async { [weak self] in
guard let self = self else { return }
// ...
self.setUpLoadingAnimation()
// ...
print("tapped 2")
self.crawlWebsite {
print("tapped 3")
self.hideLoadingView()
print("tapped 4")
}
}
}
并在 setUpLoadingAnimation()
中删除 DispatchQueue.main.async
,因为该函数已在主线程中调用。你也可以在这个函数中做view.isHidden = false
//MARK: setupLoadingAnimation
func setUpLoadingAnimation(){
self.view.addSubview(self.coverView)
self.coverView.topAnchor.constraint(equalTo: self.wishView.topAnchor).isActive = true
self.coverView.leadingAnchor.constraint(equalTo: self.wishView.leadingAnchor).isActive = true
self.coverView.trailingAnchor.constraint(equalTo: self.wishView.trailingAnchor).isActive = true
self.coverView.bottomAnchor.constraint(equalTo: self.wishView.bottomAnchor).isActive = true
self.loadingAnimation.contentMode = .scaleAspectFit
self.loadingAnimation.translatesAutoresizingMaskIntoConstraints = false
self.coverView.addSubview(self.loadingAnimation)
self.loadingAnimation.centerXAnchor.constraint(equalTo: self.coverView.centerXAnchor).isActive = true
self.loadingAnimation.centerYAnchor.constraint(equalTo: self.coverView.centerYAnchor).isActive = true
self.loadingAnimation.heightAnchor.constraint(equalToConstant: 100).isActive = true
self.loadingAnimation.widthAnchor.constraint(equalToConstant: 100).isActive = true
self.loadingAnimation.loopMode = .loop
self.loadingAnimation.play()
self.view.isHidden = false
}
和 crawlWebsite
你可以保持原样:
//MARK: crawlWebsite
func crawlWebsite(finished: @escaping () -> Void){
var html: String?
guard let url = self.url else { return }
let directoryURL = url as NSURL
let urlString: String = directoryURL.absoluteString!
// save url to wish
self.wishView.link = urlString
DispatchQueue.main.async { [weak self] in
guard let self = self else { finished(); return }
html = self.getHTMLfromURL(url: url)
self.getContentFromHTML(html: html,url: url)
self.getOpenGraphData(urlString: urlString) {
finished()
}
}
}
我希望这可以解决您面临的问题。
,我认为您使用了太多异步。你只需要在结果视图准备好时停止你的动画。所以你的结构应该是立即播放动画,在后台抓取网站,当它完成时,停止动画并显示结果。
所以有两个队列,craw在后台队列中,当它准备好时,从后台队列运行主队列中的async停止动画并显示结果。
,在后台线程加载数据(所以不影响UI)并只在主队列上发送完成回调,如
func crawlWebsite(finished: @escaping () -> Void){
var html: String?
guard let url = self.url else { return }
let directoryURL = url as NSURL
let urlString: String = directoryURL.absoluteString!
// save url to wish
self.wishView.link = urlString
DispatchQueue.global(qos: .background).async { [weak self] in
guard let self = self else {
DispatchQueue.main.async {
finished()
}
return
}
html = self.getHTMLfromURL(url: url)
self.getContentFromHTML(html: html,url: url)
self.getOpenGraphData(urlString: urlString) {
DispatchQueue.main.async {
finished()
}
}
}
}
,
我没有使用 Lottie-Animation 的经验,但我看到这段代码中至少有 2 个问题。
-
很多不需要的
DispatchQueue.main.async
调用。删除所有,并重写crawlWebsite
函数,就像上面建议的那样,结合 async global 和 async main。 -
在
setUpLoadingAnimation
函数中,确保您只添加一次子视图和设置约束,对于其他调用,例如使用hidden
属性。
最后一个 DispatchQueue.main.async 就够了
//MARK: crawlWebsite
func crawlWebsite(finished: @escaping () -> Void){
var html: String?
guard let url = self.url else { return }
let directoryURL = url as NSURL
let urlString: String = directoryURL.absoluteString!
// save url to wish
self.wishView.link = urlString
DispatchQueue.main.async { [weak self] in
guard let self = self else { finished(); return }
html = self.getHTMLfromURL(url: url)
self.getContentFromHTML(html: html,url: url)
self.getOpenGraphData(urlString: urlString) {
finished()
}
}
}
删除所有其他 DispatchQueue.main.async