[英]Swift How to wait for callback to finish before exiting function?
我對此請求的問題是第一個函數syncRequest始終返回nil,因為函數退出(回復,錯誤)回來填寫我的返回字典。
有沒有辦法讓它在返回我的閉包之前等待回調返回?
public typealias KKWatchSyncResponse = Dictionary<String, AnyObject>
func syncRequest() -> KKWatchSyncResponse? {
var syncResponseDict : KKWatchSyncResponse?
createRequest(KKWatchRequest.Sync, parameter: nil) { reply, error in
if reply == nil || error != nil {
return
} else {
syncResponseDict = KKWatchSyncResponse()
}
if let songInfo = NSKeyedUnarchiver.unarchiveObjectWithData(reply!["songInfo"] as NSData) as NSDictionary? {
syncResponseDict!["songInfo"] = songInfo
}
if let albumArtImage = NSKeyedUnarchiver.unarchiveObjectWithData(reply!["albumArt"] as NSData) as? UIImage {
syncResponseDict!["albumArtImage"] = albumArtImage
}
if let isPlaying = NSKeyedUnarchiver.unarchiveObjectWithData(reply!["isPlaying"] as NSData) as? Bool {
syncResponseDict!["isPlaying"] = isPlaying
}
}()
return syncResponseDict
}
func createRequest(request:KKWatchRequest, parameter: KKWatchAPIRequestParameter?, callback:KKWatchAPICallback) -> KKWatchAPIParentRequest {
var requestDict : Dictionary<String, AnyObject> = [KKBOXWatchAppRequestType : request.rawValue]
if parameter != nil {
requestDict += parameter! //Combine 2 dictionaries
}
return { WKInterfaceController.openParentApplication(requestDict){ reply, error in
callback(reply, error)
}
}
}
非常感謝您的幫助!
你可以讓syncRequest()
接受一個在准備好后調用結果的閉包嗎? 將定義更改為:
func syncRequest(callback:(KKWatchSyncResponse?)->Void) { ... }
然后在createRequest()
調用結束時,您可以在syncResponseDict
上調用回調,因為現在它已經填充了您的數據... callback(syncResponseDict)
。
編輯:這是我想到的解決方案。
func syncRequest(callback:(KKWatchSyncResponse?)->Void) {
createRequest(KKWatchRequest.Sync, parameter: nil) { reply, error in
if reply == nil || error != nil {
callback(nil)
} else {
var syncResponseDict : KKWatchSyncResponse? = KKWatchSyncResponse()
if let songInfo = NSKeyedUnarchiver.unarchiveObjectWithData(reply!["songInfo"] as NSData) as NSDictionary? {
syncResponseDict!["songInfo"] = songInfo
}
if let albumArtImage = NSKeyedUnarchiver.unarchiveObjectWithData(reply!["albumArt"] as NSData) as? UIImage {
syncResponseDict!["albumArtImage"] = albumArtImage
}
if let isPlaying = NSKeyedUnarchiver.unarchiveObjectWithData(reply!["isPlaying"] as NSData) as? Bool {
syncResponseDict!["isPlaying"] = isPlaying
}
callback(syncResponseDict)
}
}()
}
實現鎖定變量是很簡單的。 這對於執行某些異步網絡加載的單元測試最有幫助。
func waitingFunction()
{
//set a lock during your async function
var locked = true
RunSome.asyncFunction() { () -> Void in
//after your sync function remove the lock
locked = false
})
//wait for the async method to complete before advancing
while(locked){wait()}
//move on from the lock
doMoreStuff()
}
func wait()
{
NSRunLoop.currentRunLoop().runMode(NSDefaultRunLoopMode, beforeDate: NSDate(timeIntervalSinceNow: 1))
}
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