用程序動態改變UITextField的鍵盤模式

 [txtPhone setKeyboardType:(UIKeyboardType)];

//其中UIKeyBoardType定義如下：

typedef enum {
    UIKeyboardTypeDefault,                // Default type for the current input method.
    UIKeyboardTypeASCIICapable,           // Displays a keyboard which can enter ASCII characters, non-ASCII keyboards remain active
    UIKeyboardTypeNumbersAndPunctuation,  // Numbers and assorted punctuation.
    UIKeyboardTypeURL,                    // A type optimized for URL entry (shows . / .com prominently).
    UIKeyboardTypeNumberPad,              // A number pad (0-9). Suitable for PIN entry.
    UIKeyboardTypePhonePad,               // A phone pad (1-9, *, 0, #, with letters under the numbers).
    UIKeyboardTypeNamePhonePad,           // A type optimized for entering a person's name or phone number.
    UIKeyboardTypeEmailAddress,           // A type optimized for multiple email address entry (shows space @ . prominently).

    UIKeyboardTypeAlphabet = UIKeyboardTypeASCIICapable, // Deprecated

} UIKeyboardType;