ios - 为UIPickerView didSelectRow返回NSArray中字符串的第一个字符

Question

我有一个UIPickerView，它返回带有4 NSArray的strings。当用户滚动UIPickerView时，UITextField将使用所选行进行更新。我想返回string中每个NSArray的第一个字符，并用该字符更新UITextField。

从代码中可以看到，我尝试使用self.noiseLevelArray = [noiseArray sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];来实现此功能，我在几个不同的堆栈溢出问题中找到了它。

这是选择器的代码:

// Noise picker
self.noisePicker = [[UIPickerView alloc]init];
[noisePicker setDataSource:self];
[noisePicker setDelegate:self];
self.noiseArray = [[NSArray alloc]initWithObjects:@"4: Extreme Noise (Impossible)", @"3: Very Noisy (Loud Shouting)", @"2: Noisy (Shouting)", @"1: Not Noisy (Normally)", nil];
//self.noiseLevelArray = [noiseArray sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];

// Call noisePicker method
[self noisePickerTextField];

这是我的选择器的代码:

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

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
    return [noiseArray count];
    //return [noiseLevelArray count];
}

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
    return [noiseArray objectAtIndex:row];
    //return [noiseLevelArray objectAtIndex:row];
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    NSString *noiseString = [[NSString alloc]initWithFormat:@"%@", [noiseArray objectAtIndex:row]];
    //NSString *noiseString = [noiseLevelArray objectAtIndex:0];
    if ([self.empNoise1 isFirstResponder]) {
        self.empNoise1.text = noiseString;
    }
    else if ([self.empNoise2 isFirstResponder]) {
        self.empNoise2.text = noiseString;
    }
...

如您所见，无论UITextField中选择了哪一行，string都会更新为完整的UIPickerView。我希望它仍然显示完整的string，但仅使用第一个字符(在这种情况下为UITextField)更新1, 2, 3, or 4。任何帮助深表感谢!

Answer 1

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    NSString *noiseString = [[NSString alloc]initWithFormat:@"%@", [[noiseArray objectAtIndex:row] substringToIndex:1]];
    //NSString *noiseString = [noiseLevelArray objectAtIndex:0];
    if ([self.empNoise1 isFirstResponder]) {
        self.empNoise1.text = noiseString;
    }
    else if ([self.empNoise2 isFirstResponder]) {
        self.empNoise2.text = noiseString;
    }
}

尝试这个。它使用以下方法:

NSString * firstLetter = [word substringToIndex:1];