我对此版本的loadingOverlay单例存在一些问题。
应该发生什么，是它出现在屏幕上，带有视图和带有文字的标签，＆＃34;正在加载，请稍候。＆＃34;或类似的东西。然后，如果加载时间超过2秒（我已将其更改为10以进行调试），则文本将更改为随机可爱短语。
首先应该改变文本的动画似乎不会发生。相反，文本只是瞬间改变。
更重要的是，如果由于某种原因，我的异步调用块被多次执行，我只希望运行它的最近一次调用，并且我希望它的先前实例在运行之前终止。
我正在阅读有关回调和承诺的内容，这看起来很有希望。这是一个很好的模式吗？
顺便说一下，当我学习swift和iOS时，我一直在尝试，我尝试了[unowned self]，现在我正在尝试[弱自我]，但我和＃39;我不确定哪个最合适。
// from http://stackoverflow.com/questions/33064908/adding-removing-a-view-overlay-in-swift/33064946#33064946
import UIKit
class LoadingOverlay{
static let sharedInstance = LoadingOverlay()
//above swifty singleton syntax from http://krakendev.io/blog/the-right-way-to-write-a-singleton
var overlayView = UIView()
var spring: CASpringAnimation!
var springAway: CASpringAnimation!
var hidden = false
private init() {} //This line prevents others from using the default () initializer for this class
func setupSpringAnimation(startY: CGFloat, finishY: CGFloat) {
overlayView.layer.position.y = startY
spring = CASpringAnimation(keyPath: "position.y")
spring.damping = 10
spring.fromValue = startY
spring.toValue = finishY
spring.duration = 1.0
spring.fillMode = kCAFillModeBackwards
}
func showOverlay() {
print("show overlay")
overlayView.alpha = 1
hidden = false
if let appDelegate = UIApplication.sharedApplication().delegate as? AppDelegate,
let window = appDelegate.window {
setupSpringAnimation(-window.frame.height / 2, finishY: window.frame.height / 2)
let overlayViewFramesize = 0.65 * min(window.frame.height, window.frame.width)
overlayView.frame = CGRectMake(0, 0, overlayViewFramesize, overlayViewFramesize)
overlayView.center = window.center
overlayView.backgroundColor = UIColor.greenColor()
overlayView.clipsToBounds = true
overlayView.layer.cornerRadius = overlayViewFramesize / 8
let label = UILabel(frame: CGRectMake(0,0,overlayViewFramesize * 0.8 , overlayViewFramesize))
label.text = " \nLoading, please wait\n "
label.tag = 12
overlayView.addSubview(label)
label.lineBreakMode = NSLineBreakMode.ByWordWrapping
label.numberOfLines = 0 //as many as needed
label.sizeToFit()
label.textAlignment = NSTextAlignment.Center
label.center = CGPointMake(overlayViewFramesize / 2, overlayViewFramesize / 2)
overlayView.bringSubviewToFront(label)
window.addSubview(overlayView)
overlayView.layer.addAnimation(spring, forKey: nil)
RunAfterDelay(10.0) {
if self.hidden == true { return }
//strongSelf boilerplate code technique from https://www.raywenderlich.com/133102/swift-style-guide-april-2016-update?utm_source=raywenderlich.com+Weekly&utm_campaign=ea47726fdd-raywenderlich_com_Weekly4_26_2016&utm_medium=email&utm_term=0_83b6edc87f-ea47726fdd-415681129
UIView.animateWithDuration(2, delay: 0, options: [UIViewAnimationOptions.CurveEaseInOut, UIViewAnimationOptions.BeginFromCurrentState, UIViewAnimationOptions.TransitionCrossDissolve], animations: { [weak self] in
guard let strongSelf = self else { return }
(strongSelf.overlayView.viewWithTag(12) as! UILabel).text = randomPhrase()
(strongSelf.overlayView.viewWithTag(12) as! UILabel).sizeToFit()
print ((strongSelf.overlayView.viewWithTag(12) as! UILabel).bounds.width)
(strongSelf.overlayView.viewWithTag(12) as! UILabel).center = CGPointMake(overlayViewFramesize / 2, overlayViewFramesize / 2)
}, completion: { (finished: Bool)in
print ("animation to change label occured")})
}
}
}
func hideOverlayView() {
hidden = true
UIView.animateWithDuration(1.0, delay: 0.0, options: [UIViewAnimationOptions.BeginFromCurrentState], animations: { [unowned self] in
//I know this is clunky... what's the right way?
(self.overlayView.viewWithTag(12) as! UILabel).text = ""
self.overlayView.alpha = 0
}) { [unowned self] _ in
//I know this is clunky. what's the right way?
for view in self.overlayView.subviews {
view.removeFromSuperview()
}
self.overlayView.removeFromSuperview()
print("overlayView after removing:", self.overlayView.description)
}
//here i have to deinitialize stuff to prepare for the next use
}
deinit {
print("Loading Overlay deinit")
}
}