swift中，textField中：
//3. username/phone number textFiled
let textFieldPaddingX:CGFloat = 10
let textFieldPaddingY:CGFloat = 20
let textFieldHeight:CGFloat = 40
usernameTextField.frame = CGRectMake(
textFieldPaddingX,
appNameLabel.frame.origin.y + appNameLabel.frame.height + 40,//self.view.bounds.height*0.4,
self.view.bounds.width - (textFieldPaddingX * 2),
textFieldHeight)
usernameTextField.textAlignment = NSTextAlignment.Left
usernameTextField.font = UIFont.systemFontOfSize(16)
usernameTextField.borderStyle = UITextBorderStyle.RoundedRect
usernameTextField.placeholder = "请输入用户名（手机号）"
usernameTextField.autocorrectionType = UITextAutocorrectionType.No
usernameTextField.keyboardType = UIKeyboardType.Default
usernameTextField.returnKeyType = UIReturnKeyType.Done
usernameTextField.clearButtonMode = UITextFieldViewMode.WhileEditing
usernameTextField.contentVerticalAlignment = UIControlContentVerticalAlignment.Center
//4. password textFiled
passwordTextField.frame = CGRectMake(
usernameTextField.frame.origin.x,
usernameTextField.frame.origin.y + usernameTextField.frame.height + textFieldPaddingY,
usernameTextField.frame.width,
usernameTextField.frame.height)
passwordTextField.textAlignment = NSTextAlignment.Left
passwordTextField.font = UIFont.systemFontOfSize(16)
passwordTextField.borderStyle = UITextBorderStyle.RoundedRect
passwordTextField.placeholder = "请输入密码"
passwordTextField.secureTextEntry = true
passwordTextField.autocorrectionType = UITextAutocorrectionType.No
passwordTextField.keyboardType = UIKeyboardType.Default
passwordTextField.returnKeyType = UIReturnKeyType.Done
passwordTextField.clearButtonMode = UITextFieldViewMode.WhileEditing
passwordTextField.contentVerticalAlignment = UIControlContentVerticalAlignment.Center键盘可以出现，但是点击完成后，键盘不能消失：
搜：
swift keyboard show and dismiss
参考：
用代码：
class LoginViewController: UIViewController, UITextFieldDelegate {
//3. username/phone number textFiled
。。。
usernameTextField.delegate = self
//4. password textFiled
。。。
passwordTextField.delegate = self
/***************************************************************************
* UITextFieldDelegate Functions
***************************************************************************/
//called when 'return' key pressed. return NO to ignore.
func textFieldShouldReturn(textField: UITextField) -> Bool
{
textField.resignFirstResponder()
return true;
}点击Done后，键盘就可以消失了：
