ios - 从 Appdelegate 实例化 View Controller

Question

如果收到推送通知并且用户点击它，我将通过以下代码加载特定的 View Controller :

let tabbarController = storyboard.instantiateViewControllerWithIdentifier("employerTabBarViewController") as! UITabBarController
tabbarController.selectedIndex = 0

self.window?.rootViewController = tabbarController
let navigationController = tabbarController.viewControllers?.first as!     UINavigationController
var applicantsVC = storyboard.instantiateViewControllerWithIdentifier("ApplicantsViewController") as! ApplicantsViewController
applicantsVC.job = job

navigationController.pushViewController(applicantsVC, animated: false)
self.window?.makeKeyAndVisible()

我的问题是:此代码是否会针对每个点击的通知消息一遍又一遍地实例化 ViewController，以便智能手机的内存得到越来越多的使用？如果是这种情况，我可以在初始化新 View Controller 之前删除所有已通过应用程序的先前使用初始化的 View Controller 吗？是popToRootViewController有帮助吗？

** 更新 **我尝试了您的两个建议，但每次点击通知消息时，内存使用量都会增加约 10 MB。也许它与我在 AppDelegate 中初始化 ViewController 的方法无关，但与我加载“ApplicantsViewController”或使用 let storyboard = UIStoryboard(name: "Main", bundle: nil) 初始化 Storyboard 的方式相关。造成这种效果吗？

这是 ApplicantsViewController 的初始化(我还取消了 reloadData() 和 var tableViewController = UITableViewController() 的注释 - 这并没有阻止内存增加):

@IBOutlet weak var tableView: UITableView!
@IBOutlet weak var openPositionsStatus: UILabel!
@IBOutlet weak var changeJobOfferStatusButton: UIBarButtonItem!

var job : JobOffer?
var favorites = [Employee]()
var applicants = [Employee]()
var applications = [Application]()
var takenPositions = 0
var refreshControl : UIRefreshControl?
var offeredJobsVC : OfferedJobsViewController?

required init(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "receiveNotification:", name: "refreshApplicants", object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "receiveNotification:", name: "jobOfferStatusChanged", object: nil)
}


deinit {
    NSNotificationCenter.defaultCenter().removeObserver(self)
}

override func viewDidLoad() {
    super.viewDidLoad()
    tableView.dataSource = self
    tableView.delegate = self

    Helper.setBackground(self)

    refreshControl = UIRefreshControl()
    refreshControl!.addTarget(self, action: Selector("reloadData"), forControlEvents: UIControlEvents.ValueChanged)

    self.updateJobOfferActionButton(self, jobOffer: self.job!, button: self.changeJobOfferStatusButton)


    var tableViewController = UITableViewController()
    tableViewController.tableView = self.tableView
    tableViewController.refreshControl = refreshControl
    // call reloadData after refreshControl solved sorting problems
    reloadData()

}

Answer 1

是的，它会导致越来越多的ViewController堆积在Navigation Controller中。我的选择是在 appDelegate 中创建一个全局变量

var applicantsVC:ApplicantsViewController?

在通知函数中，执行如下操作:

if (applicantsVC == nil){
     self.applicantsVC = storyboard.instantiateViewControllerWithIdentifier("ApplicantsViewController") as! ApplicantsViewController
}