UIPickerView 选择行不起作用 ios7

Question

我有一个 UIPickerView 被“推送”到 UINavigationController，如下所示：

 [self.navigationController pushViewController:vc animated:YES];

我想设置选中的行。

我在 ViewDidAppear 中添加了：

for (int i = 0; i < [countryCodes count]; i++)
    {
        if ([[countryCodes objectAtIndex:i] isEqualToString:selectedCountryCode]){
            [_countryPicker selectRow:i inComponent:0 animated:YES];
            countrySelectedRow = i;
            break;
        }

    }
    [_countryPicker reloadAllComponents];

其中 i 是动态的（根据该视图控制器中正在更改的数据进行更改）

只有在我重新启动应用程序时才有效。

如果我在导航中来回切换它不起作用

如何让 UIPickerView 选择正确的行？

我可以在调试模式下看到 viewDidAppear 中的行被调用。也许组件正在创建，我无法更改它？

这就是我创建 UIPickerView 的方式：

- (void)viewDidLoad
{
_countryPicker = [[UIPickerView alloc] init];
    [self initPicker:_countryPicker textField:_countryText];
}

- (void)initPicker:(UIPickerView*)pickerView textField:(UITextField*) textField
{
    CGRect pickerFrame = CGRectMake(0, 0, 200, 216);
    pickerView.frame = pickerFrame;
    pickerView.userInteractionEnabled = YES;
    pickerView.dataSource = self;
    pickerView.hidden = YES;
    pickerView.delegate = self;
    pickerView.showsSelectionIndicator = YES;
    [self.view addSubview:pickerView];
    [textField setInputView:pickerView];

    textField.delegate = self;
    [pickerView removeFromSuperview];

}

Answer 1

您写道：“其中 i 是动态的（根据该视图控制器中正在更改的数据进行更改）”” 在您的代码中，i 是一个局部变量。你的意思是selectedCountryCode 吗？

for (int i = 0; i < [countryCodes count]; i++)
{
    if ([[countryCodes objectAtIndex:i] isEqualToString:selectedCountryCode]){
        [_countryPicker selectRow:i inComponent:0 animated:YES];
        countrySelectedRow = i;
        break;
    }
}
[_countryPicker reloadAllComponents];

我很确定selectedCountryCode 没有正确更新。加NSLog(selectedCountryCode);查看。

更新：

似乎问题出在您未在问题中发布的代码中。要检查我创建的代码并共享一个项目。请在这里找到它https://github.com/Avtolic/SOHelper如果你检查它你会发现一切正常。

Answer 2

设置选定的行后，您可以调用它...

[_countryPicker reloadAllComponents];

那会抹杀你的选择吗？我会删除那行

Answer 3

如果您将selectedCountryCode 变量作为单例类的一部分（例如AppDelegate 或其他一些），然后将值等同起来，这肯定会起作用。在这里，我不明白即使在视图弹出后，selectedCountryCode 是如何被保留的。

我尝试将字符串作为 AppDelegate 的一部分（这当然不是一个好习惯。应该将它放在另一个单例类中）。

#import "CViewController.h"
#import "AppDelegate.h"


@interface CViewController ()<UITextFieldDelegate, UIPickerViewDelegate, UIPickerViewDataSource>

@property(nonatomic, strong) UIPickerView *countryPicker;
@property (nonatomic, weak) IBOutlet UITextField *countryText;
@property (nonatomic, strong) NSArray *countryCodes;
@property (nonatomic, assign) int countrySelectedRow;
@property (nonatomic,strong) AppDelegate *delegate;

@end

@implementation CViewController


- (void)viewDidLoad
{
    self.delegate = [[UIApplication sharedApplication] delegate];
    _countryPicker = [[UIPickerView alloc] init];
    [self initPicker:_countryPicker textField:_countryText];
    self.countryCodes = @[@"A", @"B", @"C", @"D", @"E"];
}

- (void)initPicker:(UIPickerView*)pickerView textField:(UITextField*) textField
{
    CGRect pickerFrame = CGRectMake(0, 0, 200, 216);
    pickerView.frame = pickerFrame;
    pickerView.userInteractionEnabled = YES;
    pickerView.dataSource = self;
    pickerView.hidden = YES;
    pickerView.delegate = self;
    pickerView.showsSelectionIndicator = YES;
    [self.view addSubview:pickerView];
    [textField setInputView:pickerView];

    textField.delegate = self;

    [pickerView removeFromSuperview];
}

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

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

// returns the # of rows in each component..
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    return [self.countryCodes count];
}

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

    self.delegate.selectedCountryCode = [self.countryCodes objectAtIndex:row];
    NSLog(@"picker was(is): %d",[_countryPicker selectedRowInComponent:0]);
}


-(void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];

    for (int i = 0; i < [self.countryCodes count]; i++)
    {
        if ([[self.countryCodes objectAtIndex:i] isEqualToString:self.delegate.selectedCountryCode]){
            [_countryPicker selectRow:i inComponent:0 animated:YES];
            self.countrySelectedRow = i;
            break;
        }

    }
    [_countryPicker reloadAllComponents];
}

-(void)textFieldDidBeginEditing:(UITextField *)textField
{
    self.countryPicker.hidden = NO;
}