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
}
}
