Question

我正在尝试将VC推送到其他VC。到目前为止，我已经处理了WITH cte AS ( SELECT AVG(height) a, STDDEV(height) sd FROM people ) SELECT AVG(height) FROM people WHERE height BETWEEN (SELECT a-2*sd FROM cte) AND (SELECT a+2*sd FROM cte);个文件。因此，现在转到情节提要，我遇到了一个小问题。我有两个情节提要.xib和A.storyboard

我尝试过的是：

B.storyboard

这对我来说很好，但是我担心内存泄漏。我知道并喜欢的另一种方式是：

let storyBoard: UIStoryboard = UIStoryboard(name: storyboard, bundle: nil)

let newViewController = storyBoard.instantiateViewController(withIdentifier: storyboardId) 

controller.present(newViewController, animated: true, completion: nil)

但是，当我使用此^时，黑屏却什么也没有。为什么推送在这里不起作用，但是在self.navigationController?.pushViewController(LoginController(), animated: true)中对我来说效果很好？

Answer 1

您的第一个代码是正确的，但不是强制性的，而是一个礼物。因此，您应该这样更改代码：

Sub subTest()

    Dim arrStrings() As String

    For i = 1 To 6
        ReDim Preserve arrStrings(1 To i)       '   Extend the array - 'preserve' retains the old values too
        arrStrings(i) = "this is string " & i
    Next i

    For Each strValue In arrStrings
        Debug.Print (strValue)                  '   Just so we see each string
    Next strValue

    Debug.Print (fncDoSomething(arrStrings))    '   Passing string array as parameter

End Sub
                                                '   Example function which counts how many characters are in your array.
Function fncDoSomething(ByRef strings() As String) As Integer    '   ByRef is important when passing an array.

    Dim intCharCount As Integer
    Dim strValue As Variant
    intCharCount = 0

    For Each strValue In strings
        intCharCount = intCharCount + Len(strValue)
    Next strValue

    fncDoSomething = intCharCount

End Function

第二个代码的问题是let storyBoard: UIStoryboard = UIStoryboard(name: storyboard, bundle: nil) let newViewController = storyBoard.instantiateViewController(withIdentifier: storyboardId) self.navigationController?.pushViewController(newViewController, animated: true, completion: nil)不是情节提要中的登录控制器—只是一个新的空白LoginController。

Swift 4 push在Storyboard中不起作用

1 个答案: