objective-c - OC中动态创建可变数组的问题

Question

现有一数组，内有10个元素，已按元素的某一属性排序（比如时间字符串）。现在需要将数组中时间相同的元素取出，放入一个小数组中，再将这些小数组放入一个大数组中，请问该如何操作？最好有代码。此前都因为指针和变量作用域的问题而无法解决。

Answer 1

Use NSMutableArray
NSMutableArray * arr2=[NSMutableArray array];//The first step: define an empty variable array

arr2=[NSMutableArray addObject:obj];//The second step is to put the elements you need inside. Your search method is not clearly written, so I only give you a rough idea here

NSMutableArray *arrF=[NSMutableArray addObject:arr2];//Construct a two-dimensional variable array

NSString * str = [[arrF ObjectAtIndex: (large array subscript)] ObjectAtIndex: (small array subscript)]; // Access elements in the array