UIPickerView 没有重新加载

Question

我在我的示例应用程序中使用了 UIPickerView，但我遇到了这个问题，即除了第一行之外它不会重新加载数据。我实际上编码以独立分配选择器的第一行，但其他行与数组一起加载。每次用户按下按钮时，UIPickerView 的值都应该重新加载，但除了第一行之外，没有任何值会按预期发生变化，因为我无法弄清楚我哪里出错了。下面是我的代码

//PickerView Code....
 - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
if (pickerView.tag == 1) {
    return 1;
}
else if (pickerView.tag == 2)
{
    return 1;
}
return 0;
 }
  - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
if (pickerView.tag == 1) {
    return [self.CityList count];
}
else
{
    return [self.KmArray count];
}
return 0;
  }


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

    - (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
  {
if (pickerView.tag == 1) {
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, pickerView.frame.size.width, 44)];
    // label.backgroundColor = [UIColor grayColor];
    label.textColor = [UIColor whiteColor];
    label.font = [UIFont fontWithName:@"HelveticaNeue" size:20];
    label.textAlignment = NSTextAlignmentCenter;
    label.text = self.CityList[row];
    return label;
}
else if (pickerView.tag == 2)
{

    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, pickerView.frame.size.width, 44)];
    // label.backgroundColor = [UIColor grayColor];
    label.textColor = [UIColor whiteColor];
    label.font = [UIFont fontWithName:@"HelveticaNeue" size:20];
    label.textAlignment = NSTextAlignmentCenter;
    if (row == 0) {
        if ([_currentCity isEqual:@"Chennai"])
        {
            __weak NSString *lbl1 = [NSString stringWithFormat:@"1.8 Km"];
            lbl1 = [lbl1 stringByAppendingString:@"              "];
            lbl1 = [lbl1 stringByAppendingString:@"25.00"];
            label.text = lbl1;
            return label;
        }
        else if ([_currentCity isEqual:@"Banglore"])
        {
            __weak NSString *lbl1 = [NSString stringWithFormat:@"1.9 Km"];
            lbl1 = [lbl1 stringByAppendingString:@"              "];
            lbl1 = [lbl1 stringByAppendingString:@"25.00"];
            label.text = lbl1;
            return label;
        }
        else if ([_currentCity isEqual:@"Delhi"])
        {
            __weak NSString *lbl1 = [NSString stringWithFormat:@"2.0 Km"];
            lbl1 = [lbl1 stringByAppendingString:@"              "];
            lbl1 = [lbl1 stringByAppendingString:@"25.00"];
            label.text = lbl1;
            return label;
        }
        else if ([_currentCity isEqual:@"Mumbai"])
        {
            __weak NSString *lbl1 = [NSString stringWithFormat:@"1.5 Km"];
            lbl1 = [lbl1 stringByAppendingString:@"              "];
            lbl1 = [lbl1 stringByAppendingString:@"15.00"];
            label.text = lbl1;
            return label;
        }
        else if ([_currentCity isEqual:@"Puducherry"])
        {
            __weak NSString *lbl1 = [NSString stringWithFormat:@"1.8 Km"];
            lbl1 = [lbl1 stringByAppendingString:@"              "];
            lbl1 = [lbl1 stringByAppendingString:@"25.00"];
            label.text = lbl1;
            return label;
        }
        else if ([_currentCity isEqual:@"Pune"])
        {
            __weak NSString *lbl1 = [NSString stringWithFormat:@"1.5 Km"];
            lbl1 = [lbl1 stringByAppendingString:@"              "];
            lbl1 = [lbl1 stringByAppendingString:@"17.00"];
            label.text = lbl1;
            return label;
        }
    }
    else
    {
    __weak NSString *lbl1 = [NSString stringWithFormat:@"%@", self.KmArray[row]];
    lbl1 = [lbl1 stringByAppendingString:@"              "];
    lbl1 = [lbl1 stringByAppendingString:[NSString stringWithFormat:@"%@", self.fareArray[row]]];
    label.text = lbl1;
    return label;
    }
}
return 0;
}
  - (IBAction)GetFare:(id)sender
   {
[self.ScrollView setAlpha:1];
NSInteger row = [_SelectCity selectedRowInComponent:0];
self.currentCity = [[NSString alloc] initWithFormat:@"%@", [_CityList objectAtIndex:row]];
NSLog(@"Selected city is %@", _currentCity);
[self populatePickerArray];
[_FareList reloadAllComponents];
}
  -(void)populatePickerArray
{
float z=0.0, x = 0.0, ch = 25.0, mu = 15, pu = 17;
float y = 0.0, chd = 1.9, del = 2.1, mud = 1.6, blore = 2.0, pud = 1.6, pudd = 1.9;
if ([_currentCity isEqual:@"Chennai"])
{
    x = ch;
    y = chd;
    z = 1.2;
    [self.FareList reloadAllComponents];
}
else if ([_currentCity isEqual:@"Banglore"])
{
    x = ch ;
    y = blore;
    z = 1.3;
    [self.FareList reloadAllComponents];

}
else if ([_currentCity isEqual:@"Delhi"])
{
    x = ch ;
    y = del;
    z = 0.8;
    [self.FareList reloadAllComponents];

}
else if ([_currentCity isEqual:@"Mumbai"])
{
    x = mu ;
    y = mud;
    z = 1.0;
    [self.FareList reloadAllComponents];

}
else if ([_currentCity isEqual:@"Pune"])
{
    x = pu ;
    y = pud;
    z = 1.16;
    [self.FareList reloadAllComponents];

}
else
{
    x = ch;
    y = pudd;
    z = 1.5;
    [self.FareList reloadAllComponents];
}
float i = x;
for (float weight = y; weight <= 25.01; weight = weight + 0.1)
{
    i = i + z;
    //[_KmArray addObject:[NSNumber numberWithFloat:weight]];
    NSString *weightString = [NSString stringWithFormat:@"%0.1f Km", weight];
    [_KmArray addObject:weightString];
    NSString *fareString = [NSString stringWithFormat:@"%0.2f", i];
    [_fareArray addObject:fareString];
}
}

Answer 1

确保在 both 您的选择器视图上调用了 populatePickerArray 并在调用 reloadAllComponents 之后立即调用。

除此之外，您的代码是混乱和冗余的。您应该考虑为您的选择器视图创建一个单独的对象，以使代码更具可读性。

请注意，约定是变量不以大写字母开头。因此，cityList，而不是CityList。大写首字母为类和一些常量保留。