How to sort Custom array which contains date object - ios

Question

I have an NSArray which contains custom objects like this:
NSArray *array = {
students,students
}
And student object in turns store values like :
student.name,
student.class,
student.admissionDate
student.school ..etc
Now I want an NSArray which contains all the student's detail sorted in based on their admissionDate.
I tried using NSSortDecriptor but it doesn't helped me.
EDIT
After some hard work I have successfully formed a NSMutable array of NSDictionary which Looks like:
for(Student *arr in array)
{
NSMutableDictionary *dict;
dict = [[NSMutableDictionary alloc]init];
[dict setObject:arr.stuName forKey:#"name"];
[dict setObject:arr.stuAdate forKey:#"date"];
[dict setObject:arr.stuClass forKey:#"class"];
[expenseArray addObject:dict];
}
Printing description of expenseArray:
<__NSArrayM 0x7fe703833f70>(
{
name = uuu;
Adate = "2015-10-10 10:56:03 +0000";
class = 1st;
},
{
name = abc;
Adate = "2015-10-07 11:10:00 +0000";
class = 3rd;
},
{
name = btw;
Adate = "2015-10-10 11:13:47 +0000";
class = 4th;
}
)
Now how can i sort based on date

Answer 1

The sort descriptor should work for you
NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:#"admissionDate" ascending:YES];
NSArray *sortedStudents = [studentArray sortedArrayUsingDescriptors:#[sortDescriptor]];
Below is the working example
NSMutableArray *studentArray = [NSMutableArray new];
for (int i = 0; i < 8; i++) {
Student *student = [Student new];
unsigned int randomInterval = arc4random();
student.admissionDate = [NSDate dateWithTimeIntervalSinceNow:randomInterval];
[studentArray addObject:student];
}
for (Student *student in studentArray) {
NSLog(#"%#", student.admissionDate);
}
NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:#"admissionDate" ascending:YES];
NSArray *sortedStudents = [studentArray sortedArrayUsingDescriptors:#[sortDescriptor]];
NSLog(#"\n\n * * * * * After Sorting * * * * * *\n\n");
for (Student *student in sortedStudents) {
NSLog(#"%#", student.admissionDate);
}
Logs
2024-02-11 23:47:47 +0000
2093-11-13 21:49:48 +0000
2042-04-06 23:53:28 +0000
2032-12-23 01:49:46 +0000
2102-12-28 23:08:06 +0000
2058-10-17 14:14:27 +0000
2142-02-01 07:19:34 +0000
2048-05-14 07:07:04 +0000
* * * * * After Sorting * * * * * *
2024-02-11 23:47:47 +0000
2032-12-23 01:49:46 +0000
2042-04-06 23:53:28 +0000
2048-05-14 07:07:04 +0000
2058-10-17 14:14:27 +0000
2093-11-13 21:49:48 +0000
2102-12-28 23:08:06 +0000
2142-02-01 07:19:34 +0000

Answer 2

A sort descriptor should work fine
NSSortDescriptor *admissionSort = [NSSortDescriptor sortDescriptorWithKey:#"Adate" ascending:NO];
NSArray *sortedArray = [array sortedArrayUsingDescriptors:#[admissionSort]];
will sort the array based on the admission date assuming that is actually a NSDate value.

Answer 3

Although NSSortDescription seems to be the best way to sort an array, here is alternative approach:
NSArray *studentsArray = #[someStudent1, someStudent2];
NSArray *sortedStudentsArray = [studentsArray sortedArrayUsingComparator:^NSComparisonResult(Student *student1, Student *student2) {
return [student1.admissionDate compare:student2.admissionDate];
}];

Answer 4

NSSortDescriptor works fine!
You should replace your mutable dictionary with Student class.
#interface Student : NSObject
#property NSString *name;
#property NSString *className;
#property NSString *schoolName;
#property NSDate *admissionDate;
#end
#implementation Student
#end
Uses of this class
Student *student1 = [[Student alloc] init];
student1.name = #"Name a";
student1.className = #"4th";
student1.schoolName = #"XYZ High school";
student1.admissionDate = [NSDate dateWithTimeIntervalSinceNow:60 * 60 * 24]; // 60 * 60 * 24 one day time interval in second
Student *student2 = [[Student alloc] init];
student2.name = #"Name b";
student2.className = #"5th";
student2.schoolName = #"XYZ High school";
student2.admissionDate = [NSDate date]; // current date
NSArray *array = [NSArray arrayWithObjects:student1,student2, nil];
NSSortDescriptor *descriptor = [NSSortDescriptor sortDescriptorWithKey:#"admissionDate" ascending:YES];
NSArray *sortedArray = [array sortedArrayUsingDescriptors:#[descriptor]];
for (Student *student in sortedArray) {
NSLog(#"admissionDate %#", student.admissionDate);
}
Please keep in mind that [array sortedArrayUsingDescriptors:#[descriptor]] return sorted array, not rearranged array elements itself.
Hope this will work.