Question

我正在编写一个程序，该程序使用单个组件实现UIPickerView，以选择和显示来自两个阵列（时间和月份）的数据。第一个数组包含3行，第二个数组包含12.行程序首先显示包含三个项目的数组。当我选择'Month'按钮显示第二个数组时，只显示前三个月而不是全部12个。

如果我选择'Time-of-Day'按钮，程序会崩溃，表示：

"*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** `-[__NSArrayI objectAtIndex:]: index 3 beyond bounds [0 .. 2]'"`.

我不确定为什么它会超出数组大小。

有人可以帮我理解我需要做的事情：

更正我的代码以允许选择器视图在选择“月份”按钮时显示所有12个月
在显示月份后，在选择'Time-Of-Day'按钮时防止程序崩溃。

以下是代码......

标题

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>

@property (strong, nonatomic) IBOutlet UITextField *todTxtField;
@property (strong, nonatomic) IBOutlet UITextField *monthTxtField;

@property (strong, nonatomic) NSArray *todArray;
@property (strong, nonatomic) NSArray *monthArray;

@property (strong, nonatomic) IBOutlet UIPickerView *thePickerView;

- (IBAction)monthBtnAction:(id)sender;
- (IBAction)todBtnAction:(id)sender;

@end

实施

#import "ViewController.h"

@interface ViewController () 
@end

@implementation ViewController

@synthesize todArray, monthArray;
@synthesize thePickerView;
@synthesize monthTxtField, todTxtField;

int buttonTouched = 0;

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.todArray = [[NSArray alloc] initWithObjects:@"AM", @"Mid-Day", @"PM", nil];
    self.monthArray =[[NSArray alloc] initWithObjects: @"January", @"February", @"March", @"April",  @"May",  @"June", @"July", @"August", @"September", @"October", @"November", @"December", nil];
}

- (void) viewDidAppear:(BOOL)animated
{
    //set default rows of UITextFields to an initial state
    monthTxtField.text = @"January";
    todTxtField.text = @"Mid-Day";
}

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

#pragma mark Button Actions

- (IBAction)todBtnAction:(id)sender
{
    buttonTouched = 0;
    [thePickerView reloadAllComponents];
}

- (IBAction)monthBtnAction:(id)sender
{
    buttonTouched = 1;
    [thePickerView reloadAllComponents];
}

#pragma mark Picker

// returns the number of components to be used
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 1;
}


// returns the # of rows in the components
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:NSInteger)component
{
    switch (buttonTouched)
    {
        case 0:
            return [todArray count];
            break;
        default:
            return [monthArray count];
            break;
    }
}

//Display the row number from the array
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    switch (buttonTouched)
    {
        case 0:
            return [todArray objectAtIndex:row];
            break;
        default:
            return [monthArray objectAtIndex:row];
            break;
     }
}

//Display the row content from the array
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    switch (buttonTouched)
    {
        case 0:
           self.todTxtField.text = [todArray objectAtIndex:row];
           break;
        default:
           self.monthTxtField.text = [monthArray objectAtIndex:row];
           break;
     }
}

@end

Answer 1

如果组件0中当前选定的行大于2，当您将组件0翻转为表示具有3个成员的数组而不是具有12个成员的数组时，它肯定会崩溃。因此，在您从月份数组转换到上午/下午之前，您需要调用

[picker selectRow:0 inComponent:0 animated:YES]

否则，选择器将尝试选择12月的第11行，例如，每次只有三个范围异常翻转...

编辑..摘要.. UIPickerView有一个你没有考虑的变量，每个组件中当前选择的行。重新加载数据不会改变这个变量，你需要小心一点......

在一个UIPickerView组件中显示来自2个阵列的数据

1 个答案: