如何设置一个常量在if语句的范围之外使用？

Question

我有三个全局变量：

var activeTextField = UITextField() // stores the last textFieldDidBeginEditing 
var activeTextView = UITextView() // stores the last textViewDidBeginEditing 
var lastTextKindIsTextView = true // indicates if the last text used is a UITextView 

我想算第一个响应的文本字段或文本视图中选定的字符数。我尝试了这段代码，但它不工作，因为activeField超出了范围。有没有办法做到这一点？

if lastTextKindIsTextView { 
    let activeField = activeTextView 
} else { 
    let activeField = activeTextField 
} 

// see the length of the selected string 
var strLength = 0 

// don't work because activeField is out of scope: 
if let textRange = activeField.selectedTextRange { 
    let selectedText = activeField.text(in: textRange) 
    strLength = (selectedText?.utf16.count)! 
} 

Answer 1

的if - else表达

let activeField : UITextInput 
if lastTextKindIsTextView { 
    activeField = activeTextView 
} else { 
    activeField = activeTextField 
} 

或之前声明变量，而不if - else

let activeField : UITextInput = lastTextKindIsTextView ? activeTextView : activeTextField