iphone - 如何从选择器列表中获取值并执行计算？

Question

我需要创建两个下拉列表（选择器视图）并检索用户在两个下拉列表中选择的值并对它们执行计算？是否可以在 Xcode 中创建下拉列表？

Answer 1

Maybe try a two-component picker view.

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
return 2;
}

Say you have two arrays, self.firstArray and self.secondArray to populate the two components.

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row    forComponent:(NSInteger)component reusingView:(UIView *)view
{
if (component == 0) {
    UILabel *numberLabel = [[UILabel alloc] init];
    NSString *numberString = [self.firstArray objectAtIndex:row];
    numberLabel.font = [UIFont systemFontOfSize:14];
    numberLabel.text = numberString;
    return numberLabel;
} else {
    UILabel *alphabetLabel = [[UILabel alloc] init];
    NSString *alphabet = [self.secondArray objectAtIndex:row];
    alphabetLabel.font = [UIFont systemFontOfSize:14];
    alphabetLabel.text = alphabet;
    return alphabetLabel;
}
}

Then you can get to the user selected values like this:

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:   (NSInteger)component
{
NSLog(@"selected number: %@", self.firstArray[[self.pickerView selectedRowInComponent:0]]);
NSLog(@"selected alphabet: %@", self.secondArray[[self.pickerView selectedRowInComponent:1]]);
}