我想在开始输入时将文本字段颜色的底层更改为蓝色

I want to change bottom layer of text field color when i start typing to blue

func designTextField()
    {
        //Set the horizontal line in bottom of text field
        nameLayer.frame = CGRect(x: 0, y: self.tfName.bounds.size.height-1, width: self.tfName.bounds.size.width, height: 1)
        nameLayer.backgroundColor = UIColor.lightGray.cgColor
        tfName.layer.addSublayer(nameLayer)

        //Set the horizontal line in bottom of text field
        phoneLayer.frame = CGRect(x: 0, y: self.tfPhone.bounds.size.height-1, width: self.tfPhone.bounds.size.width, height: 1)
        phoneLayer.backgroundColor = UIColor.lightGray.cgColor
        tfPhone.layer.addSublayer(phoneLayer)

        //Set the horizontal line in bottom of text field
        emailLayer.frame = CGRect(x: 0, y: self.tfEmail.bounds.size.height-1, width: self.tfEmail.bounds.size.width, height: 1)
        emailLayer.backgroundColor = UIColor.lightGray.cgColor
        tfEmail.layer.addSublayer(emailLayer)
    }

何时使用此功能在视图中显示:

override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

        //Text Field Design
        self.designTextField()

        self.view.layoutIfNeeded()
    }

输出:

当点击 "Name" 文本字段时,底层背景颜色将变为蓝色。但是当我在文本字段中输入一些字符时,文本字段底部颜色将变为浅灰色(但当我输入时,底层将相同为蓝色。)

输出:

func textFieldDidBeginEditing(_ textField: UITextField)
    {
        if textField == self.tfName
        {
            nameLayer.backgroundColor = UIColor(red: 11/255, green: 174/255, blue: 250/255, alpha: 1).cgColor
            imgName = UIImage(named: "user2")!
            imgVwName.image = imgName
            tfName.leftView = imgVwName
        }
        else if textField == self.tfPhone
        {
            phoneLayer.backgroundColor = UIColor(red: 11/255, green: 174/255, blue: 250/255, alpha: 1).cgColor
            imgPhone = UIImage(named: "phone2")!
            imgVwPhone.image = imgPhone
            tfPhone.leftView = imgVwPhone
        }
        else if textField == self.tfEmail
        {
            emailLayer.backgroundColor = UIColor(red: 11/255, green: 174/255, blue: 250/255, alpha: 1).cgColor
            imgEmail = UIImage(named: "mail2")!
            imgVwEmail.image = imgEmail
            tfEmail.leftView = imgVwEmail
        }
    }

    func textFieldDidEndEditing(_ textField: UITextField)
    {
        if textField == self.tfName
        {
            nameLayer.backgroundColor = UIColor.lightGray.cgColor
            imgName = UIImage(named: "user1")!
            imgVwName.image = imgName
            tfName.leftView = imgVwName
        }
        else if textField == self.tfPhone
        {
            phoneLayer.backgroundColor = UIColor.lightGray.cgColor
            imgPhone = UIImage(named: "phone1")!
            imgVwPhone.image = imgPhone
            tfPhone.leftView = imgVwPhone
        }
        else if textField == self.tfEmail
        {
            emailLayer.backgroundColor = UIColor.lightGray.cgColor
            imgEmail = UIImage(named: "mail1")!
            imgVwEmail.image = imgEmail
            tfEmail.leftView = imgVwEmail
        }
    }

有人能帮忙吗???

我建议您使用 SkyFloatingField,因为它是满足您要求的轻量级库。

当您在文本字段中写入时 viewDidLayoutSubviews 每次都会被调用并调用 designTextField(designTextField 添加一个带有 grayColor 的新子层)。你可以检查是否是第一次带标志,或者在viewWillAppear或viewDidAppear中调用designTextField,或者检查图层是否被添加。