pickerview越界错误

Question

我在做城市选择这个项目时，当我快速的滚动省份名称和城市名称的时候会出现越界错误，有没有那种比较好的方法去分别控制这俩列的滚动状态。

Answer 1

这种级联加载的问题，是不是可以加些策略。当省份最终停止时，才开始加载显示城市的数组。
先参考这个博文看看：http://ikrboy.iteye.com/blog/2003127

Answer 2

#pragma  - UIPickerView DataSource-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{
    NSInteger index = pickerView.tag;
    NSInteger rows  = 0;
    if (index == 1001) {
        rows = _genderPickerViewArray.count;
    }else if (index == 1002){
        if (component == 0) {
            rows = _cityPickerViewArray.count;
        }else{
            NSInteger selectedRow  = [pickerView selectedRowInComponent:0];
            rows = ((ProvinceModel*)_cityPickerViewArray[selectedRow]).citys.count;
        }
    }
    return rows;
}-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
    NSInteger index  = pickerView.tag;
    NSInteger groups = 0;
    if (index == 1001) {
        groups = 1;
    }else if (index == 1002){
        groups = 2;
    }
    return groups;
}#pragma  - UIPickerView Delegate-(NSString*) pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
    NSInteger index = pickerView.tag;
    NSString * title  = @"";
    if (index == 1001) {
        title = _genderPickerViewArray[row];
    }else if (index == 1002){
        if (component == 0) {
            ProvinceModel * model = (ProvinceModel*)_cityPickerViewArray[row];
            title = model.provinceName;
        }else{
            NSInteger selectedRow  = [pickerView selectedRowInComponent:0];
            ProvinceModel * provModel = (ProvinceModel*)_cityPickerViewArray[selectedRow];
            // 数组越界保护
            if (row >= provModel.citys.count) {
                title = @"";
            }else{
                CityModel     * cityModel = (CityModel*)provModel.citys[row];
                title = cityModel.cityName;
            }
        }
    }
    return title;
}- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{
    NSInteger index = pickerView.tag;
    if (index == 1001) {
        _genderLabel.text = _genderPickerViewArray[row];
        _genderNumber = [self getGenderNumWithString:_genderLabel.text];
    }else if (index == 1002){
        if (component == 0) {
            // component=0 每次变化, component=1刷新一次, 且默认选中index=0
            // 同时调用一次本方法, 解决界面刷新问题.
            [_pickerViewCity reloadComponent:1];
            [_pickerViewCity selectRow:0 inComponent:1 animated:NO];
            [self pickerView:pickerView didSelectRow:[pickerView selectedRowInComponent:1] inComponent:1];
        }else{
            NSInteger selectedRow  = [pickerView selectedRowInComponent:0];
            ProvinceModel * provModel = (ProvinceModel*)_cityPickerViewArray[selectedRow];
            // 数组越界保护
            if (row >= provModel.citys.count) {
                _cityLabel.text = @"";
            }else{
                CityModel     * cityModel = (CityModel*)provModel.citys[row];
                _cityLabel.text = cityModel.cityName;
            }
        }
    }
}

Answer 3

[self preforSelector:@selector(XXX:) afterDelay:1];
配合
[NSObject cancelPreviousPerformRequestsWithTarget:self];
来实现

Answer 4

亲们，你们解决了这个问题了吗？
我提供一个思路：使用一个NSArray保存上一次的城市数据，然后对此nsarray操作。