无法在 NSUserDefaults 中保存 UIPickerView 值

Question

有两行的 UIPickerView 。尝试将每行的值保存在 NSUserDefaults 中。之前没有使用过NSUserDefaults。这是我的代码：

-(void)viewWillAppear: (BOOL) animated {
    NSUserDefaults *defaultsPicker = [NSUserDefaults standardUserDefaults];
    picker = [defaultsPicker objectForKey:@"picker"] ;
}

- (void)viewDidLoad {

    NSArray *ar1 = [NSArray array];
    for (int i = 150; i <= 210; i++)
        ar1 = [ar1 arrayByAddingObject:[NSString stringWithFormat:@"%d",i]];
    [ar1 retain];
    self.array1 = ar1;

    NSArray *ar2 = [NSArray array];
    for (int j = 40; j <= 130; j++)
        ar2 = [ar2 arrayByAddingObject:[NSString stringWithFormat:@"%d",j]];
    [ar2 retain];
    self.array2 = ar2;


    [super viewDidLoad];

}

NSUserDefaults 在 IBAction 中

-(IBAction)calculate {
    NSUserDefaults *defaultsPicker = [NSUserDefaults standardUserDefaults];
    [defaultsPicker setObject:[NSNumber numberWithInt:[picker selectedRowInComponent:0 ]] forKey:@"picker"];
    [defaultsPicker synchronize];

    //bla bla
}

当我按下按钮时，应用程序崩溃并日志为：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFNumber selectedRowInComponent:]: unrecognized selector sent to instance 0x690df40'

更新

#pragma mark -
#pragma mark Picker Data Source Methods
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 2;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component {
    if (component == secondArrayComponent) {
        return [self.array2 count];
    }else {
        return [self.array1 count];
    }
}


#pragma mark Picker Delegate Methods
- (NSString *)pickerView:(UIPickerView *)pickerView
             titleForRow:(NSInteger)row forComponent:(NSInteger)component {
    if (component == secondArrayComponent) {
        return [self.array2 objectAtIndex:row];
    }else {
        return [self.array1 objectAtIndex:row];
    }
}

Answer 1

在您的 - (void)pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
委托方法添加以下代码，它应该保存到 NSUserDefaults

UPDATE

#pragma mark -
#pragma mark Picker Data Source Methods
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 2;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component {
    if (component == secondArrayComponent) {
        return [self.array2 count];
    }else {
        return [self.array1 count];
    }
}


#pragma mark Picker Delegate Methods
- (NSString *)pickerView:(UIPickerView *)pickerView
             titleForRow:(NSInteger)row forComponent:(NSInteger)component {
    if (component == secondArrayComponent) {
        return [self.array2 objectAtIndex:row];
    }else {
        return [self.array1 objectAtIndex:row];
    }
}

- (void)pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {    
    NSInteger selectedRow = [thePickerView selectedRowInComponent:0];
    [[NSUserDefaults standardUserDefaults] setInteger:selectedRow forKey:@"picker"];
}

只要您确保已在界面生成器或代码中将 UIPickerView 的委托设置为“self”，就应该这样做。另外，在您的 .h 文件中，确保您有

UPDATE 2
要检查您的 NSUserDefaults 是否已保存，请在您选择的 -(IBAction) 中使用这段代码

NSInteger pickerRow = [[NSUserDefaults standardUserDefaults] integerForKey:@"picker"];
NSLog(@"%i", pickerRow);