Question

我有这段代码：

        NSMutableArray *customServicesArray = [[NSMutableArray alloc] initWithCapacity: 24];
    PreferenceData *userPreferences = [PreferenceData MR_findFirstInContext: [NSManagedObjectContext MR_defaultContext]];

    //  fill the array with existing data (if any)
    customServicesArray = [NSMutableArray arrayWithObjects: userPreferences.aCustomServices1, userPreferences.aCustomServices2, userPreferences.aCustomServices3, userPreferences.aCustomServices4, userPreferences.aCustomServices5, userPreferences.aCustomServices6, userPreferences.aCustomServices7, userPreferences.aCustomServices8, userPreferences.aCustomServices9, userPreferences.aCustomServices10, userPreferences.aCustomServices11, userPreferences.aCustomServices12, userPreferences.aCustomServices13, userPreferences.aCustomServices14, userPreferences.aCustomServices15, userPreferences.aCustomServices16, userPreferences.aCustomServices17, userPreferences.aCustomServices18, userPreferences.aCustomServices19, userPreferences.aCustomServices20, userPreferences.aCustomServices21, userPreferences.aCustomServices22, userPreferences.aCustomServices23, userPreferences.aCustomServices24,nil];

    NSInteger indexSelected = [oCustomServicesPickerView selectedRowInComponent:0];
    if(customServicesArray.count > (unsigned long)indexSelected)
        [customServicesArray replaceObjectAtIndex:indexSelected withObject:textField.text];  //  check to see max number of objects; might want to insert object then
    else
        [customServicesArray insertObject:textField.text atIndex: indexSelected];

我需要在特定索引处向 customServicesArray 添加元素;显然，如果数组为空，我的工作就不起作用了。我已经尝试了 addObject 但由于缺少索引而无法正常工作。

我需要做些什么来按照我想要的方式工作？

Answer 1

如果您知道最大可能值，则可以使用[NSNull null]或其他一些虚拟对象预填充数组。

或者添加一些代码

NSInteger indexSelected = [oCustomServicesPickerView selectedRowInComponent:0];

while (customServicesArray.count <= indexSelected) {
    [customServicesArray addObject:[NSNull null]]; // Here you can add some dummy object
}

[customServicesArray replaceObjectAtIndex:indexSelected withObject: @"textFieldText"];

Answer 2

改为使用NSMutableDictionary。

customServicesDictionary[@(indexSelected)] = textField.text;

需要在NSMutableArray的特定索引处添加文本字段内容

2 个答案: