返回在iOS應用程序中被兩次調用

Question

我正在嘗試使用用戶名和密碼文本字段在我的iOS應用中實現一個非常基本的登錄屏幕。

在用戶輸入用戶名后點擊“下一步”后，我查找了如何使視圖自動聚焦於密碼文本字段。 但是，由於某些原因，似乎在用戶輸入用戶名后兩次檢測到該返回。 而不是將鍵盤保持在屏幕上並專注於密碼textField，鍵盤消失了，並且沒有textField處於焦點。

我究竟做錯了什么？

LoginViewController.m：

@implementation LoginViewController


    - (void)viewDidLoad
    {
        [super viewDidLoad];
        [self.navigationController setNavigationBarHidden:YES];
        username = [[NSString alloc]init];
        keychainItem = [[KeychainItemWrapper alloc]initWithIdentifier:@"Login" accessGroup:nil];    
    }

    // Check if user presses next from the username textfield -> automatically go to password
    - (BOOL)textFieldShouldReturn:(UITextField *)theTextField {
        if (theTextField == self.txtPassword) {
            // try logging in
            NSLog(@"trying to proceed to submit form");

        } else if (theTextField == self.txtUsername) {
            // automatically go to the password field
            NSLog(@"trying to proceed to password field");
            [self.txtPassword becomeFirstResponder];
        }
        return YES;
    }

當我查看日志時，用戶在用戶名字段中單擊“下一步”后，將顯示以下兩個日志

2014-08-27 00:11:48.594 BiP[3049:60b] trying to proceed to password field
2014-08-27 00:11:48.640 BiP[3049:60b] trying to proceed to submit form

Answer 1

嘗試這個：

- (BOOL)textFieldShouldReturn:(UITextField *)theTextField {
        if (theTextField == self.txtPassword) {
            // try logging in
            NSLog(@"trying to proceed to submit form");
            return YES;

        } else if (theTextField == self.txtUsername) {
            // automatically go to the password field
            NSLog(@"trying to proceed to password field");
            [self.txtPassword becomeFirstResponder];
            return NO;
        }
        return YES;
    }

希望這可以幫助.. ：）