我正在制作一个类似 Tinder 的应用程序,在其中我使用解析查询数组并将数据显示在一副卡片中。我有一个查询数组的方法,并在同一方法中使用返回的列表。但是,我收到错误,因为在数据下载完成之前调用了后卡。 “ fatal error :在解包可选值时意外发现 nil”
我该如何处理这个问题,以便代码等待检索查询?
谢谢
import UIKit
import MDCSwipeToChoose
class ChoosePersonViewController: UIViewController, MDCSwipeToChooseDelegate {
var people:[Person] = []
let ChoosePersonButtonHorizontalPadding:CGFloat = 80.0
let ChoosePersonButtonVerticalPadding:CGFloat = 20.0
var currentPerson:Person!
var frontCardView:ChoosePersonView!
var backCardView:ChoosePersonView!
let nameData = ""
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
let userObjectID = PFUser.currentUser()!.objectId!
let query = PFQuery(className:"Restaurants")
query.whereKey("Pointer", equalTo: userObjectID)
query.findObjectsInBackgroundWithBlock {
(objects: [PFObject]?, error: NSError?) -> Void in
if error == nil {
// The find succeeded.
print("Successfully retrieved \(objects!.count) scores.")
// Do something with the found objects
if let objects = objects {
for object in objects {
var nameData = object.objectForKey("Name") as? String
var imageData = object.objectForKey("Image") as? PFFile
imageData!.getDataInBackgroundWithBlock { (imageData, error) -> Void in
if error == nil {
if let imageData = imageData
{
let image = UIImage(data: imageData)
self.people.append(Person(name: nameData, image: image, age: 21, sharedFriends: 3, sharedInterest: 4, photos: 5))
print(self.people)
}
}
}
}
}
} else {
// Log details of the failure
print("Error: \(error!) \(error!.userInfo)")
}
}
}
override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
// Here you can init your properties
let imageData: PFFile
}
override func viewDidLoad(){
super.viewDidLoad()
// Display the first ChoosePersonView in front. Users can swipe to indicate
// whether they like or dislike the person displayed.
self.setMyFrontCardView(self.popPersonViewWithFrame(frontCardViewFrame())!)
self.view.addSubview(self.frontCardView)
// Display the second ChoosePersonView in back. This view controller uses
// the MDCSwipeToChooseDelegate protocol methods to update the front and
// back views after each user swipe.
self.backCardView = self.popPersonViewWithFrame(backCardViewFrame())!
self.view.insertSubview(self.backCardView, belowSubview: self.frontCardView)
// Add buttons to programmatically swipe the view left or right.
// See the `nopeFrontCardView` and `likeFrontCardView` methods.
constructNopeButton()
constructLikedButton()
}
func suportedInterfaceOrientations() -> UIInterfaceOrientationMask{
return UIInterfaceOrientationMask.Portrait
}
// This is called when a user didn't fully swipe left or right.
func viewDidCancelSwipe(view: UIView) -> Void{
print("You couldn't decide on \(self.currentPerson.Name)");
}
// This is called then a user swipes the view fully left or right.
func view(view: UIView, wasChosenWithDirection: MDCSwipeDirection) -> Void{
// MDCSwipeToChooseView shows "NOPE" on swipes to the left,
// and "LIKED" on swipes to the right.
if(wasChosenWithDirection == MDCSwipeDirection.Left){
print("You noped: \(self.currentPerson.Name)")
}
else{
print("You liked: \(self.currentPerson.Name)")
}
// MDCSwipeToChooseView removes the view from the view hierarchy
// after it is swiped (this behavior can be customized via the
// MDCSwipeOptions class). Since the front card view is gone, we
// move the back card to the front, and create a new back card.
if(self.backCardView != nil){
self.setMyFrontCardView(self.backCardView)
}
backCardView = self.popPersonViewWithFrame(self.backCardViewFrame())
//if(true){
// Fade the back card into view.
if(backCardView != nil){
self.backCardView.alpha = 0.0
self.view.insertSubview(self.backCardView, belowSubview: self.frontCardView)
UIView.animateWithDuration(0.5, delay: 0.0, options: .CurveEaseInOut, animations: {
self.backCardView.alpha = 1.0
},completion:nil)
}
}
func setMyFrontCardView(frontCardView:ChoosePersonView) -> Void{
// Keep track of the person currently being chosen.
// Quick and dirty, just for the purposes of this sample app.
self.frontCardView = frontCardView
self.currentPerson = frontCardView.person
}
func popPersonViewWithFrame(frame:CGRect) -> ChoosePersonView?{
if(self.people.count == 0){
return nil;
}
// UIView+MDCSwipeToChoose and MDCSwipeToChooseView are heavily customizable.
// Each take an "options" argument. Here, we specify the view controller as
// a delegate, and provide a custom callback that moves the back card view
// based on how far the user has panned the front card view.
let options:MDCSwipeToChooseViewOptions = MDCSwipeToChooseViewOptions()
options.delegate = self
//options.threshold = 160.0
options.onPan = { state -> Void in
if(self.backCardView != nil){
let frame:CGRect = self.frontCardViewFrame()
self.backCardView.frame = CGRectMake(frame.origin.x, frame.origin.y-(state.thresholdRatio * 10.0), CGRectGetWidth(frame), CGRectGetHeight(frame))
}
}
// Create a personView with the top person in the people array, then pop
// that person off the stack.
let personView:ChoosePersonView = ChoosePersonView(frame: frame, person: self.people[0], options: options)
self.people.removeAtIndex(0)
return personView
}
最佳答案
我建议在硬循环中启动所有图像下载是无效的,并且可能会导致网络洪水和多个请求超时。
考虑只存储所有返回的对象并仅请求第一个(也许是第二个)图像。
保存返回的项目后立即添加 View ,并在图像可用时将图像添加到 View 中。
看来您的问题实际上可能与尝试删除尚不存在的 View 有关,尽管尚不清楚该函数的作用,并且可能更像是想要访问一个尚未存在的对象尚未添加到数组中,因为下一个图像尚未下载,因此无法找到/创建合适的项目来返回...更改使用图像和 View 的方式将解决这些原因之一。
关于arrays - Swift:如何处理解析查询的等待时间,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/37356687/