Picker 将随机数据保存到 NSUserDefaults

Question

我一直在为一款名为 Dofus 的游戏开发一个新的提示和技巧项目。在第一个视图中，要求用户从选择器中选择 class。然后他们转到下一个视图并选择他们的级别和类似的东西。然而，选择器的问题是它从选择器中得到了错误的 class。

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

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
    return [self.classNames count];

}

- (NSString *)pickerView:(UIPickerView *)pickerView
             titleForRow:(NSInteger)row
            forComponent:(NSInteger)component {
    NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
    NSString *_myClass = self.classNames[row];
    [prefs setObject:_myClass forKey:@"class"];
    return self.classNames[row];
}

在 ViewDidLoad 中我声明了我的 classes:

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"background"]];

    self.classNames = @[@"Cra", @"Ecaflip", @"Eliotrope", @"Eniripsa",
                            @"Enutrof", @"Feca", @"Foggernout", @"Iop", @"Masqueraider", @"Osamodas", @"Pandawa", @"Rogue", @"Sacrier", @"Sadida", @"Sram", @"Xelor"];

}

然后在下一个视图中我得到这样的信息（不同的 .m 文件）：

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do view setup here.
    self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"background"]];

    NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];

    // getting an NSString
    NSString *myClass = [prefs stringForKey:@"class"];

    _textLabel.text = [NSString stringWithFormat:@"So you are a %@ huh? Pretty cool! Its a good class. Fill out the rest so we are ready to go!", myClass];
}

有人知道这是怎么回事吗？提前致谢！

Answer 1

您正在为行标题的选择器数据源调用设置首选项，而不是在选择行时的委托调用。对于加载到视图中的每一行，调用 pickerView:titleForRow:forComponent:，此时您设置 class 首选项，但是，这并不对应于在选择器中选择的行，它对应于要显示的下一行。

相反，响应 pickerView:didSelectRow:inComponent: 方法，并在那里设置您的首选项（您仍然需要响应另一个来设置行标题，只是不要设置首选项）。

- (NSString *)pickerView:(UIPickerView *)pickerView
         didSelectRow:(NSInteger) row 
         inComponent:(NSInteger) component {
    NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
    NSString *_myClass = self.classNames[row];
    [prefs setObject:_myClass forKey:@"class"];
}

Answer 2

如果你想存储用户选择的行，你应该使用 UIPickerViewDelegate

中的方法

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

类似的东西会起作用：

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
    NSString *_myClass = self.classNames[row];
    [prefs setObject:_myClass forKey:@"class"];
    [prefs synchronize];
  }
}

查看这些链接以更好地了解 UIPickerView 的工作原理：

http://nscookbook.com/2013/01/ios-programming-recipe-7-using-the-uipickerview/

http://www.techotopia.com/index.php/An_iOS_7_UIPickerView_Example

https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIPickerView_Class/index.html#//apple_ref/doc/uid/TP40006842-CH3-SW9

Picker 将随机数据保存到 NSUserDefaults

Picker saves random data to NSUserDefaults

ios

objective-c

nsuserdefaults

uipickerview