从xib文件加载ViewController

Question

我有一个MyViewController.swift和一个MyViewController.xib呈现MyViewController的布局.

我尝试了不同的方法加载这个视图控制器,包括:

//1
let myVC = UINib(nibName: "MyViewController", bundle:
       nil).instantiateWithOwner(nil, options: nil)[0] as? MyViewController

//2
let myVC = NSBundle.mainBundle().loadNibNamed("MyViewController", owner: self, options: nil)[0] as? MyViewController

//3
let myVC = MyViewController(nibName: "MyViewController", bundle: nil)

第三个是唯一成功的初始化,但前两个导致错误:

由于未捕获的异常'NSUnknownKeyException'而终止应用,

reason:'[setValue:forUndefinedKey:]:此类不是密钥XXX的密钥值编码兼容.

这些加载方法有什么问题？

Answer 1

斯威夫特3

let myViewController = MyViewController(nibName: "MyViewController", bundle: nil)
self.present(myViewController, animated: true, completion: nil)

或推入导航控制器

self.navigationController!.pushViewController(MyViewController(nibName: "MyViewController", bundle: nil), animated: true)

Answer 2

请注意File's Owner.在你的情况下,File's Owner必须是MyViewController,或者是sub-class.

以下代码,如果它在课堂上执行Foo.

// If `self` is an instance of `Foo` class.
// In this case, `File's Owner` will be a `Foo` instance due to `self` parameter.
let myVC = NSBundle.mainBundle().loadNibNamed("MyViewController", owner: self, options: nil)[0] as? MyViewController

它通过self了owner.所以,File's Owner是Foo,不是MyViewController.然后,对于Foo课堂,那些IBOutlet不能连接Foo,那些File's Owner是为了File's Owner.所以,它崩溃了.

Answer 3

extension UIViewController {
    static func loadFromNib() -> Self {
        func instantiateFromNib<T: UIViewController>() -> T {
            return T.init(nibName: String(describing: T.self), bundle: nil)
        }

        return instantiateFromNib()
    }
}

使用它如下：

let testVC = TestVC.loadFromNib()

Answer 4

尝试下面的代码，

//1

let nib = UINib(nibName: "MyViewController", bundle:nil)
myVC = nib.instantiateWithOwner(self, options: nil)[0] as? MyViewController

或者

myVC = nib.instantiateWithOwner(self, options: nil).first as? MyViewController

//2

let nib : NSArray = NSBundle.mainBundle().loadNibNamed("MyViewController", owner: self, options: nil)
myVC = nib.objectAtIndex(0) as? MyViewController

这会起作用。