对于带输入框的弹出框（UIAlertView）,在IOS5.0及以上版本，有一种较为简单的实现方式，即设置UIAlertView的alertViewStyle属性即可。

可供设置的属性如下:

typedef NS_ENUM(NSInteger, UIAlertViewStyle) {
    UIAlertViewStyleDefault = 0,
    UIAlertViewStyleSecureTextInput,
    UIAlertViewStylePlainTextInput,
    UIAlertViewStyleLoginAndPasswordInput
};

UIAlertViewStyleDefault，为默认值，不带输入框
UIAlertViewStyleSecureTextInput为密码型输入框，输入的字符显示为圆点儿
UIAlertViewStylePlainTextInput为明文输入框，显示输入的实际字符
UIAlertViewStyleLoginAndPasswordInput为用户名，密码两个输入框，一个明文，一个密码。

取得输入框指针的方法如下：
对于UIAlertViewStyleSecureTextInput和UIAlertViewStylePlainTextInput两种情况，
UITextField *tf = [alert textFieldAtIndex:0]即可取到输入框指针，然后可以进行具体的操作，包括设置键盘样式
对于UIAlertViewStyleLoginAndPasswordInput，除了上面的输入框，依次类推，还可以取到第二个输入框，即：
UITextField *tf2 = [alert textFieldAtIndex:1]

设置键盘样式的方法，即设置UITextField的keyboardType属性。具体值如下：

typedef NS_ENUM(NSInteger, UIKeyboardType) {
    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).
#if __IPHONE_4_1 <= __IPHONE_OS_VERSION_MAX_ALLOWED
    UIKeyboardTypeDecimalPad,             // A number pad with a decimal point.
#endif
#if __IPHONE_5_0 <= __IPHONE_OS_VERSION_MAX_ALLOWED
    UIKeyboardTypeTwitter,                // A type optimized for twitter text entry (easy access to @ #)
#endif
 
    UIKeyboardTypeAlphabet = UIKeyboardTypeASCIICapable, // Deprecated
 
};

示例代码：

－ (IBAction)pressed:(id)sender
    {
        UIAlertView* alert = [[UIAlertView alloc] initWithTitle:@"message"
                                                        message:@"please input"
                                                       delegate:nil
                                              cancelButtonTitle:@"cancel"
                                              otherButtonTitles:@"OK", nil];
        // 基本输入框，显示实际输入的内容
        alert.alertViewStyle = UIAlertViewStylePlainTextInput;
        // 用户名，密码登录框
    //    alert.alertViewStyle = UIAlertViewStyleLoginAndPasswordInput;
        // 密码形式的输入框，输入字符会显示为圆点
    //    alert.alertViewStyle = UIAlertViewStyleSecureTextInput;
         
        //设置输入框的键盘类型
        UITextField *tf = [alert textFieldAtIndex:0];
        tf.keyboardType = UIKeyboardTypeNumberPad;
         
        UITextField *tf2 = nil;
        if (alert.alertViewStyle == UIAlertViewStyleLoginAndPasswordInput) {
            // 对于用户名密码类型的弹出框，还可以取另一个输入框
            tf2 = [alert textFieldAtIndex:1];
            tf2.keyboardType = UIKeyboardTypeASCIICapable;
        }
         
        // 取得输入的值
        NSString* text = tf.text;
        NSLog(@"INPUT:%@", text);
        if (alert.alertViewStyle == UIAlertViewStyleLoginAndPasswordInput) {
            // 对于两个输入框的
            NSString* text2 = tf2.text;
            NSLog(@"INPUT2:%@", text2);
        }
         
        [alert show];
    }

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http://bluevt.org/?p=103
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