Question

当用户按下按钮时，图像会变为开启状态。当用户离开视图控制器时，我需要它记住按钮在下次进入此VC时设置为图像。我试过NSUser默认无效。有人可以帮忙吗？

在按钮操作中：

  buttonPressed = !buttonPressed

    let defaults = NSUserDefaults.standardUserDefaults()


    if buttonPressed == true {

        let followedObjectId = userToShowDetail?["name"] as? String

        isFollowing[followedObjectId!] = true

        sender.setImage(UIImage(named: "fave_on@2x.png"), forState: UIControlState.Normal)
        print("follow")

        let following = PFObject(className: "Followers")
        following["following"] = userToShowDetail?["name"] as? String
        following["follower"] = PFUser.currentUser()?.objectId
        favLabel.text = "Favourite Jammer"

        following.saveInBackground()
        defaults.setBool(true, forKey: "SwitchState")

    } else {

        if buttonPressed != true {
            let followedObjectId = userToShowDetail?["name"] as? String

            isFollowing[followedObjectId!] = false
            print("notFollow")
            sender.setImage(UIImage(named: "fave_off@2x.png"), forState: UIControlState.Normal)

            favLabel.text = "Add to favourites?"

            defaults.setBool(false, forKey: "SwitchState")

在视图中加载：

  // save switch state:
    let defaults = NSUserDefaults.standardUserDefaults()
    if (defaults.objectForKey("SwitchState") != nil) {
        buttonPressed = defaults.boolForKey("SwitchState")
    }

Answer 1

尝试下面的解决方案。每次单击按钮，它都会打开和关闭状态。如果您离开视图控制器，它将保存状态。如果这对您有帮助，请告诉我。

@contextmanager
def make_session_scope(Session):
    """Provide a transactional scope around a series of operations."""
    session = Session()
    session.expire_on_commit = False
    try:
        yield session
        session.commit()
    except:
        session.rollback()
        raise
    finally:
        session.close()

 with make_session_scope(session) as session:
      query = session.query(model)

Answer 2

您只需在AppDelegate

中存储此类内容即可

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate{

    var myButtonSwitchState: Bool = false


    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        //your code...
    }    

    //the rest of your code...

}

然后，在您的视图控制器中，您可以通过将UIApplication.sharedApplication().delegate投射到AppDelegate

来获取您的应用委托

var appDelegate: AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

然后，您只需在app delegate

中获取并设置布尔值即可

func getSwitchState() -> Bool{
    return appDelegate.myButtonSwitchState
}

func setSwitchState(value: Bool){
    appDelegate.myButtonSwitchState = value
}

如果您希望在用户退出应用后将此状态存储起来（将其从正在运行的应用中删除），则可以使用NSUserDefaults而只需使用此代码

func getSwitchState() -> Bool{
    return NSUserDefaults.standardUserDefaults().boolForKey("buttonStatus")
}

func setSwitchState(value: Bool){
    NSUserDefaults.standardUserDefaults().setObject(value, forKey: "buttonStatus")
    NSUserDefaults.standardUserDefaults().synchronize()
}

保存按钮图像的状态很快

2 个答案: