準(zhǔn)備工作（以下代碼不用寫）

typedef NS_ENUM(NSInteger, UIAlertControllerStyle) {
   UIAlertControllerStyleActionSheet = 0,// 從底部彈出
   UIAlertControllerStyleAlert// 從中心彈出
} NS_ENUM_AVAILABLE_IOS(8_0);

typedef NS_ENUM(NSInteger, UIAlertActionStyle) {
   UIAlertActionStyleDefault = 0,
   UIAlertActionStyleCancel,
   UIAlertActionStyleDestructive
} NS_ENUM_AVAILABLE_IOS(8_0);

上干貨

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"文本對話框" message:@"登錄和密碼對話框" preferredStyle:UIAlertControllerStyleAlert];

UIAlertAction *OKAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
    // 停止監(jiān)聽文本改變通知
    [[NSNotificationCenter defaultCenter]removeObserver:self name:UITextFieldTextDidChangeNotification object:alertController.textFields.lastObject];
    // 打印第一個文本框的內(nèi)容
    NSLog(@"%@",alertController.textFields.firstObject.text);
    
}];
[alertController addAction:OKAction];

UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil];
[alertController addAction:cancelAction];

 UIAlertAction *destructiveAction = [UIAlertAction actionWithTitle:@"警告" style:UIAlertActionStyleDestructive handler:nil];
[alertController addAction:destructiveAction];

[alertController addTextFieldWithConfigurationHandler:^(UITextField * _Nonnull textField) {
    textField.backgroundColor = [UIColor redColor];
    textField.placeholder = @"請輸用戶名";   
}];

[alertController addTextFieldWithConfigurationHandler:^(UITextField * _Nonnull textField) {
    textField.backgroundColor = [UIColor redColor];
    textField.placeholder = @"請輸入密碼";
    textField.secureTextEntry = YES;// 以圓點格式顯示
    // 設(shè)置監(jiān)聽
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(handleTextDidChangeNotification:) name:UITextFieldTextDidChangeNotification object:textField];
    
}];

// 將OK按鈕禁用
OKAction.enabled = NO;
self.alertAction = OKAction;//存儲OK按鈕

[self presentViewController:alertController animated:YES completion:nil];

從底部彈出提示框

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"OK/取消" message:@"請你登陸！" preferredStyle:UIAlertControllerStyleActionSheet];

UIAlertAction *OKaction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:nil];

UIAlertAction *cancleAction = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil];

UIAlertAction *destructiveAction = [UIAlertAction actionWithTitle:@"警告" style:UIAlertActionStyleDestructive handler:nil];

[alertController addAction:OKaction];
[alertController addAction:cancleAction];
[alertController addAction:destructiveAction];

[self presentViewController:alertController animated:YES completion:nil];