ios – 使用Firebase时使用未解析的标识符“FIRDatabase”

import UIKit
import Firebase

@UIApplicationMain
class AppDelegate: UIResponder,UIApplicationDelegate {

    var window: UIWindow?

    func application(application: UIApplication,didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        FIRApp.configure()
        FIRDatabase.database().persistenceEnabled = true // Use of unresolved identifier 'FIRDatabase'
        return true
    }
}

我在用：

Xcode 7.2.1,
Firebase 3.0.2,
OSX 10.10.5

Podfile内容：

source 'https://github.com/CocoaPods/Specs.git'
platform :ios,'8.0'
use_frameworks!

target 'myapp' do
pod 'IQKeyboardManagerSwift','<= 4.0.0'
pod 'JSQMessagesViewController','<= 7.3.1'
pod 'Firebase'
end