PickerView未显示

Question

我试图调出一个选取器视图而不是键盘放在文本字段中，但我的选取器视图没有显示。

#import "SettingsViewController.h"
#import "FindClasses.h"

@interface SettingsViewController ()
@property (weak, nonatomic) IBOutlet UIBarButtonItem *saveButton;
@property (weak, nonatomic) IBOutlet UITextField *classTextField;
@property (strong, nonatomic) UIPickerView *picker;
@property (nonatomic, strong) FindClasses *finder;
@property (nonatomic, strong) NSArray *itemsArray;
@end

@implementation SettingsViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    NSArray *itemsArray = [self.finder findClassesInTimetable];
    // Do any additional setup after loading the view.
}

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

- (void)presentPicker {
    CGRect frame = CGRectMake(0, 40, 0, 0);
    UIPickerView *picker = [[UIPickerView alloc] initWithFrame:frame];
    picker.delegate = self;
    picker.dataSource = self;
    // TODO: animate this on screen
    [self.view addSubview:picker];
}

- (void)textFieldDidBeginEditing:(UITextField *)textField {
    [self presentPicker];
}

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
    return 1;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
    return [self.itemsArray count];  //where items is your array of items
}

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row inComponent:(NSInteger)component {
    return [self.itemsArray objectAtIndex:row];
}

谁能告诉我我哪里做错了？我从另一篇Stackoverflow帖子中取了这个例子：

Answer 1

希望能对你有所帮助

 - (void)presentPicker {
        UIPickerView *picker = [[UIPickerView alloc] init];
        picker.delegate = self;
        picker.dataSource = self;
        // TODO: animate this on screen
        classTextField .delegate = self;
        classTextField.inputView = picker;
    }

 - (BOOL)textFieldShouldBeginEditing:(UITextField *)textField  {
       [textField becomeFirstResponder];
       return YES;
    }

Answer 2

这是I使用UIPickerViews的方式，示例代码如下：

UIPickerView* genderPicker = [[UIPickerView alloc] init];

genderPicker.delegate = self;

genderPicker.dataSource = self;

在初始化UITextField (在我的例子中是registrationGenderField)之后：

registrationGenderField.inputView = genderPicker;

然后是delegates和dataSources：

- (NSString *) pickerView:(UIPickerView *)pickerView
          titleForRow:(NSInteger)row
         forComponent:(NSInteger)component {

switch (row) {

        case 0:
            return @"Gender";
            break;

        case 1:
            return @"Male";
            break;

        case 2:
            return @"Female";
            break;

        default:
            return @"Gender";
            break;
    }
}

- (void) pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {

    switch (row) {

        case 0:
            registrationGenderField.text = @"";
            break;

        case 1:
            registrationGenderField.text =  @"Male";
            break;

        case 2:
            registrationGenderField.text =  @"Female";
            break;

        default:
            registrationGenderField.text =  @"";
            break;
    }
}



- (NSInteger) numberOfComponentsInPickerView:(UIPickerView *)pickerView {

    return 1;
}

- (NSInteger) pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {

    return 3;
}

Answer 3

你只需要初始化你的选择器视图即可；

并将其委托设置为self，并在.h文件中添加uipickerviewdelegate委托和数据源

然后在文本字段中开始编辑添加textField集合输入视图:拾取器；

还实现了textfieldshouldreturn