SourceKitService Crashed in Xcode 6.1.1 - ios

Question

I started having an issue with Xcode 6.0.1 where the error "SourceKitService Crashed Crashlog generated in ~/Library/Logs/DiagnosticReports" started popping up and all syntax highlighting was gone in Swift. Then Apple released a new update Xcode 6.1.1 where mentioned this issue was resolved. So I updated my Xcode to 6.1.1 but this problem still exists. I my case the issue is just staying there and never disappearing.
I tried few solutions found in StackOverflow like deleting the content of: DerivedData/ModuleCache, cleaning up the project etc but the issue still exists.
I am not able to make a build and whenever I try to get these 2 errors.
/Users/MY_PROJECT/AppDelegate.swift:11:1: 'UIApplicationMain' class must conform to the 'UIApplicationDelegate'
protocol at UIApplicationMain in my AppDelegate.h file and this Command failed due to signal: Segmentation fault: 11
Here is the code of my AppDelegate.swift
import UIKit
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(application: UIApplication!, didFinishLaunchingWithOptions launchOptions: NSDictionary!) -> Bool {
return true
}
func applicationWillResignActive(application: UIApplication!) {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
func applicationDidEnterBackground(application: UIApplication!) {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
func applicationWillEnterForeground(application: UIApplication!) {
// Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}
func applicationDidBecomeActive(application: UIApplication!) {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
func applicationWillTerminate(application: UIApplication!) {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}
}

Answer 1

I'am not sure about the cause of this error, i was getting this sourcekit crash for various reasons. For you if you look into UIApplicationDelegate methods, they are slightly changed in the signature. For eg UIApplication parameter is not optional now.
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
// Override point for customization after application launch.
return true
}
So if you compare your delegate methods with new UIApplicationDelegate methods(if you command+click you can check the method signature)and make changes you may get rid off this error. Give a try.