Ios 在文本字段中输入小写字母到大写字母，反之亦然

我使用的是Xcode 8和Swift 3。我正在为iOS创建一个应用程序。如何使输入的小写字母在文本字段中自动转换为大写字母，反之亦然？

第一个答案是可以的，但需要一些修改。在带有变音符号的字母上测试。使用复制和粘贴文本方法进行测试

下面说

class ViewController: UIViewController {

一定是这样

class ViewController: UIViewController, UITextFieldDelegate {

---

这仅适用于一个文本字段。即使在Shift键被锁定或按下时，也要强制输入大写字母

@IBOutlet weak var textField: UITextField!

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if string.lowercased() == string {
        textField.text = (textField.text! as NSString).replacingCharacters(in: range, with: string.uppercased())
    } else {
        textField.text = (textField.text! as NSString).replacingCharacters(in: range, with: string.uppercased())
    }

    return false
}

@IBOutlet weak var textField: UITextField!

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if string.lowercased() == string {
        textField.text = (textField.text! as NSString).replacingCharacters(in: range, with: string.lowercased())
    } else {
        textField.text = (textField.text! as NSString).replacingCharacters(in: range, with: string.lowercased())
    }

    return false
}

不要忘记在“override func viewDidLoad（）”中插入以下内容

---

这仅适用于一个文本字段。要强制输入小写字母，即使在Shift键被锁定或按下时

@IBOutlet weak var textField: UITextField!

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if string.lowercased() == string {
        textField.text = (textField.text! as NSString).replacingCharacters(in: range, with: string.uppercased())
    } else {
        textField.text = (textField.text! as NSString).replacingCharacters(in: range, with: string.uppercased())
    }

    return false
}

@IBOutlet weak var textField: UITextField!

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if string.lowercased() == string {
        textField.text = (textField.text! as NSString).replacingCharacters(in: range, with: string.lowercased())
    } else {
        textField.text = (textField.text! as NSString).replacingCharacters(in: range, with: string.lowercased())
    }

    return false
}

不要忘记在“override func viewDidLoad（）”中插入以下内容

---

以下是两个文本字段。假设一个文本字段始终为大写，另一个始终为小写

@IBOutlet weak var textFieldAlwaysUppercase: UITextField!

@IBOutlet weak var textFieldAlwaysLowercase: UITextField!

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if textField.isEqual(textFieldAlwaysUppercase) {
        textFieldAlwaysUppercase.text = (textField.text! as NSString).replacingCharacters(in: range, with: string.uppercased())
        return false
    } else if textField.isEqual(textFieldAlwaysLowercase) {
        textFieldAlwaysLowercase.text = (textField.text! as NSString).replacingCharacters(in: range, with: string.lowercased())
        return false
    }
    return true
}

不要忘记在“override func viewDidLoad（）”中插入以下内容

可能重复的

    textFieldAlwaysUppercase.delegate = self
    textFieldAlwaysLowercase.delegate = self