您需要移动completion(region)
到 Firebase 完成块内并添加@escaping
after completion:
.
另外,您不应该强制打开选项。很容易检查它们是否不是nil
这将防止应用程序崩溃。
func mapRegion(completion: @escaping (MKCoordinateRegion?) -> Void) {
let ref = Database.database().reference()
ref.child("RunList").child(runName).observe(.value, with: { (snapshot) in
guard
let runData = snapshot.value as? Dictionary<String,Double>,
let minLat = runData["startLat"],
let minLng = runData["startLong"],
let maxLat = runData["endLat"],
let maxLng = runData["endLong"]
else {
print("Error! - Incomplete Data")
completion(nil)
return
}
var region = MKCoordinateRegion()
region.center = CLLocationCoordinate2D(latitude: (minLat + maxLat) / 2, longitude: (minLng + maxLng) / 2)
region.span = MKCoordinateSpanMake((maxLat - minLat) * 1.1, (maxLng - minLng) * 1.1)
completion(region)
})
}
然后将您的代码更新为此。
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
mapRegion { (region) in
if let region = region {
self.mapView.setRegion(region, animated: true)
}
}
}
为您loadRuns
func loadRuns(completion: @escaping (Array<RunDetail>) -> Void) {
let ref = Database.database().reference()
ref.child("RunList").observe(.value, with: { (snapshot) in
var runs = Array<RunDetail>()
// Populate runs array.
completion(runs) // This line needs to be inside this closure.
})
}