我试图做这个扩展:
extension UIViewController { class func initialize(storyboardName: String,storyboardId: String) -> Self { let storyboad = UIStoryboard(name: storyboardName,bundle: nil) let controller = storyboad.instantiateViewControllerWithIdentifier(storyboardId) as! Self return controller } }
但我得到编译错误:
error: cannot convert return expression of type ‘UIViewController’ to
return type ‘Self’
可能吗?我也想做为init(storyboardName:String,storyboardId:String)
类似于
Using ‘self’ in class extension functions in Swift,您可以定义一个通用辅助方法,从调用上下文中推断self的类型:
extension UIViewController { class func instantiateFromStoryboard(storyboardName: String,storyboardId: String) -> Self { return instantiateFromStoryboardHelper(storyboardName,storyboardId: storyboardId) } private class func instantiateFromStoryboardHelper<T>(storyboardName: String,storyboardId: String) -> T { let storyboard = UIStoryboard(name: storyboardName,bundle: nil) let controller = storyboard.instantiateViewControllerWithIdentifier(storyboardId) as! T return controller } }
然后
let vc = MyViewController.instantiateFromStoryboard("name",storyboardId: "id")
编译,类型推断为MyViewController。
Swift 3的更新:
extension UIViewController { class func instantiateFromStoryboard(storyboardName: String,storyboardId: String) -> Self { return instantiateFromStoryboardHelper(storyboardName: storyboardName,bundle: nil) let controller = storyboard.instantiateViewController(withIdentifier: storyboardId) as! T return controller } }
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