检查文本字段是否为空

Question

我正在尝试检查文本字段是否为空，但收到 "Type (Bool, Bool, Bool) does not conform protocol 'Boolean Type' "

错误

 if(userEmail == "", userPassword == "", userRepeatPassword == "") {


        alertMessage("All fields are required")
        return

    }

我正在使用 xcode 7

Answer 1

试试这个，

if(userEmail == "" || userPassword == "" || userRepeatPassword == "") 
{
                //Do Something
}

(或)

if(userEmail == "" && userPassword == "" && userRepeatPassword == "") 
{
                //Do Something
}

Answer 2

你应该这样使用 &&:

let userEmail = "William"
let userPassword = "Totti"
let  userRepeatPassword = "Italy"


if(userEmail == "" && userPassword == "" &&  userRepeatPassword == "") {

    print("okay")

}

然而，还有另一种方法可以做到，那就是：

if(userEmail.isEmpty && userPassword.isEmpty && userRepeatPassword.isEmpty){
    print("okay")
}

另一种方法是像这样检查字符数：

if(userEmail.characters.count == 0 && userPassword.characters.count == 0 && userRepeatPassword.characters.count == 0){
    print("okay")
}

Answer 3

 if (userEmail?.isEmpty || userConfirmEmail?.isEmpty || userPassword?.isEmpty || userConfirmPassword?.isEmpty){

        alertMessage("All fields are required!");
        return;
    }

使用这个方法

Answer 4

这是检查文本字段是否为空的最简单方法：

例如：

if let userEmail = UserEmail.text, !userEmail.isEmpty,
let userPassword = UserPassword.text, !userPassword.isEmpty,
let userRepeatPassword = UserRepeatPassword.text, !userRepeatPassword.isEmpty { ... }

如果所有条件都为真，则所有变量都被展开。

Answer 5

Swift3.0以后，最好使用早期的绑定语句，让代码更清晰。

guard !(userEmail.isEmpty)! && !(userPassword.isEmpty)! && !(userRepeatPassword.isEmpty)! else {
      return
}

// 如果字段包含文本则执行某些操作

检查文本字段是否为空

Checking if text field is empty

swift

xcode7