快速为 uiTextField 添加前缀

如何解决快速为 uiTextField 添加前缀

我正在尝试将国家/地区代码作为前缀添加到 textField，以便用户可以输入其电话号码的其余部分

   @IBAction func phoneLogin(_ sender: Any) {
    let countryCode = "+1"
    
    guard let phoneNumber = countryCode + MobileLbl.text! else { return }
    
    if ((MobileLbl.text?.isEmpty) != nil) {
        print("Fill Your Number")
    }else {
        OTPtxt.isHidden = false
        VerifyBtn.isHidden = false
    PhoneAuthProvider.provider().verifyPhoneNumber(phoneNumber,uiDelegate: nil) { (verificationId,error) in
        if error == nil {
            guard let verifyId = verificationId else { return }
            self.def.setValue(verifyId,forKey: "verificationId")
            self.def.synchronize()
            
            print(verificationId)
        } else {
            print("Unable to get Secret verification from firebase",error?.localizedDescription)
        }
    }
    
    }
    
}

我收到此错误条件绑定的初始化程序必须具有可选类型，而不是“字符串”

解决方法

您强制解包 2021-01-27T12:55:26.211031+00:00 app[web.1]: [2021-01-27 12:55:26 +0000] [9] [INFO] Booting worker with pid: 9 2021-01-27T12:55:26.213834+00:00 app[web.1]: Failed to find attribute 'app' in '__main__'. 2021-01-27T12:55:26.214015+00:00 app[web.1]: [2021-01-27 12:55:26 +0000] [9] [INFO] Worker exiting (pid: 9) 2021-01-27T12:55:26.223266+00:00 app[web.1]: [2021-01-27 12:55:26 +0000] [10] [INFO] Booting worker with pid: 10 2021-01-27T12:55:26.226404+00:00 app[web.1]: Failed to find attribute 'app' in '__main__'. 2021-01-27T12:55:26.226731+00:00 app[web.1]: [2021-01-27 12:55:26 +0000] [10] [INFO] Worker exiting (pid: 10) 2021-01-27T12:55:26.359501+00:00 app[web.1]: [2021-01-27 12:55:26 +0000] [4] [INFO] Shutting down: Master 2021-01-27T12:55:26.359767+00:00 app[web.1]: [2021-01-27 12:55:26 +0000] [4] [INFO] Reason: App failed to load. 2021-01-27T12:55:26.447672+00:00 heroku[web.1]: Process exited with status 4 2021-01-27T12:55:26.511220+00:00 heroku[web.1]: State changed from starting to crashed，这不再使它成为可选的。去掉感叹号，所以它只是MobileLbl.text!。还必须将 MobileLbl.text 移到另一行，因为它也不是可选的。

countryCode