如何添加清除按钮UITextfield？

Question

我想在UITextfield中添加一个清除按钮，但它不显示。

这是UITextfield的代码：

  @implementation databaseEnterDataViewController

@synthesize customer = customer_ ;
@synthesize type = type_ ;
@synthesize code1 = code1_ ;
@synthesize code2 = code2_ ;
@synthesize background,
            changeType,
            codeOne,
            codeTwo,
            customers,
            suspendDisplayInfo,
            tf;


#pragma mark -
#pragma mark Initialization

#pragma mark -
#pragma mark View lifecycle

- (void)viewDidLoad {
    [super viewDidLoad];

    self.customer = @"" ;
    self.type     = @"" ;
    self.code1    = @"" ;
    self.code2    = @"" ;

    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"Save" style:UIBarButtonSystemItemCancel target:self action:nil];
    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemCancel target:self action:nil];
    self.navigationItem.title = @"Enter Data";

    code1Field_.clearButtonMode = UITextFieldViewModeWhileEditing;
    code2Field_.clearButtonMode = UITextFieldViewModeUnlessEditing;
    customerField_.clearButtonMode = UITextFieldViewModeAlways;


    [self openDB];
    [self createTable:@"barcodeScan" withField1:@"key" withField2:@"scanDate" withField3:@"theCustomer" withField4:@"type" withField5:@"theCode1" withField6:@"theCode2" withField7:@"discription" withField8:@"articleNr" withField9:@"batchNr" withField10:@"serialNr" withField11:@"expDate"];

    self.suspendDisplayInfo=false;
    NSLog(@"%@",typeLabel_.text);









#ifdef LOG_FILE
    NSFileManager *fileManger = [NSFileManager defaultManager];
    if ([fileManger fileExistsAtPath:[self getLogFile]])
    {
        [debug appendString:[[NSString alloc] initWithContentsOfFile:[self getLogFile]]];
        [debugText setText:debug];
    }
#endif

    dtdev=[Linea sharedDevice];
    [dtdev addDelegate:self];
    [dtdev connect];




    types = [[NSMutableArray alloc] init];
    [types addObject:@"Select barcode type"];
    [types addObject:@"Intervascular"];
    [types addObject:@"CID"];
    [types addObject:@"MAQUET"];


    [self pickerview];

    tf.clearButtonMode =UITextFieldViewModeAlways;


}




- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    // Return the number of sections.
    return 1;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    // Return the number of rows in the section.
    return 4;
}


// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView
         cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:nil];

    // Make cell unselectable
    cell.selectionStyle = UITableViewCellSelectionStyleNone;

     tf = nil;
    tf.clearButtonMode =UITextFieldViewModeAlways;
    changeType = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    changeType.frame = CGRectMake(cell.frame.origin.x + 220, cell.frame.origin.y + 7, 80, 30);
    [changeType setTitle:@"Change type" forState:UIControlStateNormal];
    changeType.backgroundColor= [UIColor clearColor];
   [changeType.titleLabel setFont:[UIFont systemFontOfSize:14]];
    [changeType addTarget:self action:@selector(clickeButton:) forControlEvents:UIControlEventTouchDown];


    switch ( indexPath.row ) {
        case 0: {
            cell.textLabel.text = @"Customer:" ;
            tf = customerField_ = [self makeTextField:self.customer placeholder:@"Customer name"];
            [cell addSubview:customerField_];


            break ;
        }
        case 1: {
            cell.textLabel.text = @"Type:" ;
            tf = typeLabel_ = [self makeTextField:self.type placeholder:@"Type code"];
            [cell addSubview:typeLabel_];
            [cell addSubview:changeType];

            break ;
        }
        case 2: {
            cell.textLabel.text = @"Code 1:" ;
            tf = code1Field_ = [self makeTextField:self.code1 placeholder:@"Code 1"];
            [cell addSubview:code1Field_];
            break ;
        }
        case 3: {
            cell.textLabel.text = @"Code 2:" ;
            tf = code2Field_ = [self makeTextField:self.code2 placeholder:@"code 2"];
            [cell addSubview:code2Field_];
            break ;
        }
    }

    // Textfield dimensions
    tf.frame = CGRectMake(120, 12, 170, 30);

    // Workaround to dismiss keyboard when Done/Return is tapped
    [tf addTarget:self action:@selector(textFieldFinished:) forControlEvents:UIControlEventEditingDidEndOnExit];

    // We want to handle textFieldDidEndEditing
    tf.delegate = self ;

    return cell;
}





-(UITextField*) makeTextField: (NSString*)text
                  placeholder: (NSString*)placeholder  {
    UITextField*tf = [[UITextField alloc] init];
    tf.placeholder = placeholder ;
    tf.text = text ;
    tf.autocorrectionType = UITextAutocorrectionTypeNo ;
    tf.autocapitalizationType = UITextAutocapitalizationTypeNone;
    tf.adjustsFontSizeToFitWidth = YES;
    tf.textColor = [UIColor colorWithRed:56.0f/255.0f green:84.0f/255.0f blue:135.0f/255.0f alpha:1.0f];
    return tf ;
}

// Workaround to hide keyboard when Done is tapped
- (IBAction)textFieldFinished:(id)sender {
    // [sender resignFirstResponder];
}

// Textfield value changed, store the new value.
- (void)textFieldDidEndEditing:(UITextField *)textField {
    if ( textField == customerField_ ) {
        self.customer = textField.text ;
    }
    else if ( textField == typeLabel_ ) {
        self.type = textField.text ;
    }
    else if ( textField == code1Field_ ) {
        self.code1 = textField.text ;
    }
    else if ( textField == code2Field_ ) {
        self.code2 = textField.text ;
    }
}

在iPhone上看起来像这样：

当我像这样添加清除按钮时

customerField_.clearButtonMode = UITextFieldViewModeWhileEditing;

按钮没有显示。

我该怎么做才能让它可见？

Answer 1

如果你使用UITextFieldViewModeAlways，如果textfield的字符串不是nil或者它的长度是＆gt;那么你会看到按钮。 0.如果没有什么可以清除的话，我认为你不能显示清除按钮。

Answer 2

如果您希望清除按钮始终可见，则需要将文本字段的clearButtonMode属性设置为UITextFieldViewModeAlways。您当前配置文本字段的方式，清除按钮仅在编辑文本字段时显示。

编辑：正如Mat在评论中指出的那样，无论文本字段的clearButtonMode属性给出了什么值，只有相关的清除按钮才会显示，也就是说，如果有什么要清除的话。如果文本字段为空，则无需显示清除按钮。