ios 类没有初始值设定项：Swift 错误

Class has no initializers: Swift Error

提问by iGermanos

I have a problem with my ViewController.

我的 ViewController 有问题。

My code has an error about initializers and I can't understand why.

我的代码有一个关于初始化程序的错误，我不明白为什么。

Please, take a moment to look at my code:

请花点时间看看我的代码：

import UIKit

class ViewController: UIViewController, UITableViewDataSource {

let sectionsTableIdentifier = "SectionsTableIdentifier"

var names: [String: [String]]!
var keys: [String]!

@IBOutlet weak var tableView: UITableView!

var searchController: UISearchController

//methods
override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    tableView.registerClass(UITableViewCell.self, forCellReuseIdentifier: sectionsTableIdentifier)

    let path = NSBundle.mainBundle().pathForResource("sortednames", ofType: "plist")

    let namesDict = NSDictionary(contentsOfFile: path!)
    names = namesDict as! [String: [String]]
    keys = namesDict!.allKeys as! [String]
    keys = keys.sort()

    let resultsController = SearchResultsController()

    resultsController.names = names
    resultsController.keys = keys
    searchController = UISearchController(searchResultsController: resultsController)

    let searchBar = searchController.searchBar
    searchBar.scopeButtonTitles = ["All", "Short", "Long"]
    searchBar.placeholder = "Enter a search term"

    searchBar.sizeToFit()
    tableView.tableHeaderView = searchBar
    searchController.searchResultsUpdater = resultsController

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    return keys.count
}

func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    let key = keys[section]
    let nameSection = names[key]!
    return nameSection.count
}

func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
    return keys[section]
}

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier(sectionsTableIdentifier, forIndexPath: indexPath) as UITableViewCell

    let key = keys[indexPath.section]
    let nameSection = names[key]!
    cell.textLabel!.text = nameSection[indexPath.row]

    return cell
}

func sectionIndexTitlesForTableView(tableView: UITableView) -> [String]? {


       return keys
    }

}

What is the problem? The error is that the class has no initializer. I have no variables with no value.

问题是什么？错误是该类没有初始化程序。我没有没有价值的变量。

回答by Sahil Kapoor

Problematic line is

有问题的线路是

var searchController: UISearchController

Change it to

将其更改为

var searchController: UISearchController!

or if you are not initializing it in view life cycles, use optional to avoid crashes:

或者如果您没有在视图生命周期中对其进行初始化，请使用 optional 来避免崩溃：

var searchController: UISearchController?

回答by jlngdt

Your line which catch the error is:

您捕获错误的行是：

var searchController: UISearchController

var searchController: UISearchController

because you never init searchController in a LifeCycle init functionfrom your UIViewController. I advice you not to force unwrapthe var (like Sahil said above) but to properly init it into an init func like this:

因为你从来没有在UIViewController的LifeCycle init 函数中初始化 searchController 。我建议你不要强制解包var（就像上面 Sahil 所说的那样），而是将它正确地初始化为一个 init func，如下所示：

override init(frame: CGRect) {
    super.init(frame: frame)

    setUp()
}

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)

    setUp()
}

func setUp() {
    searchController = UISearchController() //Or any init you can use to perform some custom initialization
}

In Swift, you always should avoid force unwrap Object like above, to avoid crash in your app, or use if-Let/Guard-Let template

在 Swift 中，你总是应该避免像上面那样强制解包 Object，以避免在你的应用程序中崩溃，或者使用 if-Let/Guard-Let 模板

Cheers from France

来自法国的欢呼