Sort 2 NSArrays By Date [duplicate] - ios

Question

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Sorting two NSArrays together side by side
(4 answers)
Closed 6 years ago.
I have 2 NSMutableArrays declared. One is filled with names and then another one is filled with string values of NSDate.
I want to sort both of them according to the date in the second one. For example if element 3 in the date array becomes element 0 I want the same to happen for the name array.
What is the easiest way to do this? I know how to sort the date array just not the corresponding name array!
(Objective-C Please!)

Answer 1

Sorting 2 arrays and keeping them in sync is a pain. You basically have to sort them by hand.
Probably the easiest way to do this is to create an array of dictionaries where each dictionary contains a data and a name.
Then sort the array of dictionaries by date.
EDIT:
Here is the code for creating custom objects containing a name and a date. There is code to sort by date as well as code to sort by name:
/**
The thing class has a property date and a property name.
It is purely for creating sorted arrays of objects
*/
#interface Thing : NSObject
#property (nonatomic, strong) NSDate *date;
#property (nonatomic, strong) NSString *name;
#end
#implementation Thing
/**
This is a dummy init method that creates a Thing ojbect with a random name and date
*/
- (instancetype) init {
self = [super init];
if (!self) return nil;
NSString *letters = #"ABCDEFGHIJKLMNOPQRSTUVWXYZ";
NSMutableString *temp = [NSMutableString new];
for (int x = 0; x < 10; x++) {
unichar aChar = [letters characterAtIndex:arc4random_uniform(26)];
[temp appendFormat: #"%C", aChar];
}
self.name = [temp copy];
//Create a random date
uint32 halfMax = 2000000000;
uint32 max = halfMax * 2;
int32_t value = arc4random_uniform(max) - halfMax;
NSTimeInterval now = [[NSDate date] timeIntervalSinceReferenceDate];
self.date = [NSDate dateWithTimeIntervalSinceReferenceDate: now + value];
return self;
}
- (NSString *) description {
return [NSString stringWithFormat: #"Name: %# Date: %#", self.name, self.date];
}
#end
int main(int argc, const char * argv[]) {
#autoreleasepool {
//Create an array of Thing objects
const int count = 50;
NSMutableArray *thingArray = [NSMutableArray arrayWithCapacity: count];
for (int x = 0; x < count; x++) {
thingArray[x] = [[Thing alloc] init];
}
#if 1
//Sort by date, ascending
[thingArray sortUsingComparator:^NSComparisonResult(Thing *obj1,
Thing *obj2) {
NSComparisonResult bigger =
[obj1.date timeIntervalSinceReferenceDate] <
[obj2.date timeIntervalSinceReferenceDate] ?
NSOrderedAscending : NSOrderedDescending;
return bigger;
}];
#else
//Sort by name
[thingArray sortUsingComparator:^NSComparisonResult(Thing *obj1,
Thing *obj2) {
return [obj1.name compare: obj2.name];
}];
#endif
NSLog(#"%#", thingArray);
}
return 0;
}