Question

这是代码：

@interface CreateAccountViewController : UIViewController<UITableViewDelegate, UITableViewDataSource, UITextFieldDelegate>
{
    UIToolbar *keyboardToolbar;
    NSDate *birthdate;
    UIActionSheet *dateSheet;
}

@property(strong, nonatomic) IBOutlet UITextField *txtFirstName;
@property(strong, nonatomic) IBOutlet UITextField *txtLastName;
@property(strong, nonatomic) IBOutlet UITextField *txtGender;
@property(strong, nonatomic) IBOutlet UITextField *txtBirthdate;
@property(strong, nonatomic) IBOutlet UITextField *txtEmail;

-(void)resignKeyboard:(id)sender;
-(void)gotoPreviousField:(id)sender;
-(void)gotoNextField:(id)sender;

-(void)setBirth;
-(void)dismissDateSet;
-(void)gotoPreviousBirthdate;
-(void)gotoNextBirthdate;

@end

@implementation CreateAccountViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    [[[keyboardToolbar items] objectAtIndex:0] setEnabled:YES];
    [[[keyboardToolbar items] objectAtIndex:1] setEnabled:YES];
    if([textField isEqual:self.txtFirstName])
    {
        [[[keyboardToolbar items] objectAtIndex:0] setEnabled:NO];
    }
    else if([textField isEqual:self.txtEmail])
    {
        [[[keyboardToolbar items] objectAtIndex:0] setEnabled:NO];
    }
}

-(BOOL)textFieldShouldBeginEditing:(UITextField *)textField
{
    if([textField isEqual:self.txtBirthdate])
    {
        [self setBirth];
        return NO;
    }
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view

    if(keyboardToolbar==nil)
    {
        keyboardToolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, 44)];

        UIBarButtonItem *btnPrevious = [[UIBarButtonItem alloc] initWithTitle:@"Previous" style:UIBarButtonItemStyleBordered target:self action:@selector(gotoPreviousField:)];

        UIBarButtonItem *btnNext = [[UIBarButtonItem alloc] initWithTitle:@"Next" style:UIBarButtonItemStyleBordered target:self action:@selector(gotoNextField:)];

        UIBarButtonItem *btnExtraSpace= [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];

        UIBarButtonItem *btnDone=[[UIBarButtonItem alloc] initWithTitle:@"Done" style:UIBarButtonItemStyleDone target:self action:@selector(resignKeyboard:)];

        [keyboardToolbar setItems:[[NSArray alloc] initWithObjects:btnPrevious, btnNext, btnExtraSpace, btnDone, nil]];
    }
}

-(void) resignKeyboard:(id)sender
{
    if([self.txtFirstName isFirstResponder])
    {
        [self.txtFirstName resignFirstResponder];
    }
    else if([self.txtLastName isFirstResponder])
    {
        [self.txtLastName resignFirstResponder];
    }
    else if([self.txtGender isFirstResponder])
    {
        [self.txtGender resignFirstResponder];
    }
    else if([self.txtBirthdate isFirstResponder])
    {
        [self.txtBirthdate resignFirstResponder];
    }
    else if([self.txtEmail isFirstResponder])
    {
        [self.txtEmail resignFirstResponder];
    }
}

-(void) gotoPreviousField:(id)sender
{
    if([self.txtFirstName isFirstResponder])
    {
        [self.txtEmail becomeFirstResponder];
    }
    else if([self.txtLastName isFirstResponder])
    {
        [self.txtFirstName becomeFirstResponder];
    }
    else if([self.txtGender isFirstResponder])
    {
        [self.txtLastName becomeFirstResponder];
    }
    else if([self.txtEmail isFirstResponder])
    {
        [self.txtBirthdate becomeFirstResponder];
    }
}

-(void)gotoNextField:(id)sender
{
    if([self.txtFirstName isFirstResponder])
    {
        [self.txtLastName becomeFirstResponder];
    }
    else if([self.txtLastName isFirstResponder])
    {
        [self.txtGender becomeFirstResponder];
    }
    else if([self.txtGender isFirstResponder])
    {
        [self.txtBirthdate becomeFirstResponder];
    }
    else if([self.txtEmail isFirstResponder])
    {
       [self.txtFirstName becomeFirstResponder];
    }

}

-(void)setBirth
{
    dateSheet=[[UIActionSheet alloc] initWithTitle:nil delegate:nil cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles:nil];
    [dateSheet setActionSheetStyle:UIActionSheetStyleDefault];

    CGRect pickerFrame=CGRectMake(0, 44, 0, 0);
    UIDatePicker *birthDayPicker=[[UIDatePicker alloc] initWithFrame:pickerFrame];
    [birthDayPicker setDatePickerMode:UIDatePickerModeDate];

    [dateSheet addSubview:birthDayPicker];

    UIToolbar *birthDayToolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, dateSheet.bounds.size.width, 44)];
    [birthDayToolbar setBarStyle:UIBarStyleBlackTranslucent];
    [birthDayToolbar sizeToFit];

    UIBarButtonItem *btnPrevious = [[UIBarButtonItem alloc] initWithTitle:@"Previous" style:UIBarButtonItemStyleBordered target:self action:@selector(gotoPreviousBirthdate:)];

    UIBarButtonItem *btnNext = [[UIBarButtonItem alloc] initWithTitle:@"Next" style:UIBarButtonItemStyleBordered target:self action:@selector(gotoNextBirthdate:)];

    UIBarButtonItem *btnExtraSpace= [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];

    UIBarButtonItem *btnDone=[[UIBarButtonItem alloc] initWithTitle:@"Done" style:UIBarButtonItemStyleDone target:self action:@selector(dismissDateSet:)];

    [birthDayToolbar setItems:[[NSArray alloc] initWithObjects:btnPrevious, btnNext, btnExtraSpace, btnDone, nil]];
    [dateSheet addSubview:birthDayToolbar];
    [dateSheet showInView:self.view];
    [dateSheet setBounds:CGRectMake(0, 0, 320, 485)];
}

-(void)dismissDateSet
{
    NSArray *listOfViews = [dateSheet subviews];
    for(UIView *subView in listOfViews)
    {
        if([subView isKindOfClass:[UIDatePicker class]])
        {
            NSDateFormatter *dateFormatter=[[NSDateFormatter alloc] init];
            [dateFormatter setDateFormat:@"MM/dd/yyyy"];
            self.txtBirthdate.text=[dateFormatter stringFromDate:[(UIDatePicker*)subView date]];
        }
    }
}

-(void)gotoPreviousBirthdate
{
    [self dismissDateSet];
    [self.txtGender becomeFirstResponder];
}

-(void)gotoNextBirthdate
{
    [self dismissDateSet];
    [self.txtEmail becomeFirstResponder];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 5;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{

    static NSString *CellIdentifier = @"CreateCellIdentifier";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }

    UITextField *textField = [[UITextField alloc] init];
    textField.enablesReturnKeyAutomatically = YES;
    textField.autocorrectionType = UITextAutocorrectionTypeNo;
    textField.autocapitalizationType = UITextAutocapitalizationTypeNone;
    textField.clearButtonMode=UITextFieldViewModeWhileEditing;
    textField.delegate=self;
    CGRect aRect=CGRectMake(10, 10.f, CGRectGetWidth(cell.bounds)-40.f, 30.f );
    textField.frame = aRect;

    if(indexPath.row==0)
    {
        textField.placeholder = @"First name";
        self.txtFirstName=textField;
    }
    else if(indexPath.row==1)
    {
        textField.placeholder = @"Last name";
        self.txtLastName=textField;
    }
    else if(indexPath.row==2)
    {
        textField.placeholder = @"Gender";
        self.txtGender=textField;
    }
    else if(indexPath.row==3)
    {
        textField.placeholder = @"Date of birth";
        self.txtBirthdate=textField;
    }
    else
    {
        textField.placeholder = @"Email";
        self.txtEmail=textField;
    }

    [cell.contentView addSubview:textField];
    cell.selectionStyle=UITableViewCellSelectionStyleNone;

    textField.inputAccessoryView=keyboardToolbar;

    return cell;

}

@end

如果我按下日期选择工具栏上的“上一步”按钮，我会收到以下异常：

[CreateAccountViewController gotoPreviousBirthdate:]: unrecognized selector sent to instance

如果我按下日期选择工具栏上的“下一步”按钮，我会收到以下异常：

[CreateAccountViewController gotoNextBirthdate:]: unrecognized selector sent to instance

如果我按下日期选择工具栏上的完成按钮，我会收到以下异常：

[CreateAccountViewController dismissDateSet:]: unrecognized selector sent to instance

似乎我犯了同样的错误3次，但我无法弄清楚那是什么。感谢

Answer 1

您将目标选择器设置为：

@selector(gotoPreviousBirthdate:)

但你宣布它为：

-(void)gotoPreviousBirthdate;

删除选择器中的：@selector(gotoPreviousBirthdate)，因为您没有参数，或将声明更改为-(void)gotoPreviousBirthday:(id)sender。

然后重复另外两个。

Answer 2

您正在调用方法，就好像它们是类方法一样，但它们在您的接口中被声明为实例方法。此外，选择器的调用也是错误的。

首先创建该类的实例：

CreateAccountViewController *vc = [[CreateAccountViewController alloc] init]; //Something like this

然后你可以调用实例方法：

[vc gotoPreviousBirthday]; //Note no trailing colon!

或者，如果您将方法声明为

+(void)gotoPreviousBirthdate;

注意签名中的+ - 然后您可以在代码显示时调用该方法。

这是Objective-C中一个非常基本的概念，所以我建议你先阅读文档。 Apple Objective-C Primer

无法识别的选择器问题

2 个答案: