About NSMutableArray add NSArray issue - iphone

Question

I want to below effect,but I don't kown how to use NSMutableArray combine NSArray More than two?
1.my code
for (int i=0; i<[DateSortArry2 count]; i++) {
for (int j=0; j<[DateSortArry2Copy count]; j++) {
NSString *sectiondateStr2 = [NSString stringWithFormat:#"%#",[DateSortArry2Copy objectAtIndex:j]];
if ([[DateSortArry2 objectAtIndex:i] isEqualToString:sectiondateStr2]) {
[Arry addObject:sectiondateStr2];
}
}
[SumArry addObjectsFromArray:Arry];
[Arry removeAllObjects];
}
2.my code Result
SumArry:(
"20130227",
"20130227",
"20130227",
"20130226",
"20130226",
"20130226",
"20130225",
"20130225")
3.I want the results
SumArry:((
"20130227",
"20130227",
"20130227",
),
(
"20130226",
"20130226",
"20130226",
),
(
"20130225",
"20130225"
))

Answer 1

Your code repeatedly fills and empties the same array by adding its elements, but you need to preserve the structure with additional instances of NSArray. So, use a new NSArray for each section.
for (int i=0; i<[DateSortArry2 count]; i++) {
NSMutableArray *section = [NSMutableArray array];
for (int j=0; j<[DateSortArry2Copy count]; j++) {
NSString *sectiondateStr2 = [NSString stringWithFormat:#"%#",[DateSortArry2Copy objectAtIndex:j]];
if ([[DateSortArry2 objectAtIndex:i] isEqualToString:sectiondateStr2]) {
[section addObject:sectiondateStr2];
}
}
[SumArry addObject:section];
}

Answer 2

You can either store a reference to another array (or any type of object) in your array:
[myMutableArray addObject:otherArray];
Or concatinate the arrays.
[myMutableArray addObjectsFromArray:otherArray];
Both of which are documented in the documentation. By the looks of it the first approach is what you want since you want to have NSArray of NSMutableArray.

Answer 3

try this:
please tell me if it works.
thanks
NSString *str = #"";
for (int i=0; i<[DateSortArry2 count]; i++)
{
if (str isEqualToString:[DateSortArry2 objectAtIndex:i])
{
return;
}
else
{
NSMutableArray * Arry = [[NSMutableArray alloc] init];
str = [DateSortArry2 objectAtIndex:i]
for (int j=0; j<[DateSortArry2Copy count]; j++)
{
if ([[DateSortArry2 objectAtIndex:i] isEqualToString:str])
{
[Arry addObject:str];
}
}
[SumArry addObject:Arry];
[Arry removeAllObjects];
}
}