I have the following block:
sortedNameArray = [nameArray sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2){
return [(NSString *)obj1 compare:(NSString *)obj2 options:NSNumericSearch];
}];
That I use to take an array of Strings and alphabetize them. Now what I want to do is get it to alphabetize an array of Name objects(an object with a NSString firstName and a NSString lastName) by looking at the last name attribute then alphabetizing the objects by its lastName attribute. Here is an example of a Name object:
Name *bobSmith = [[Name alloc] init];
[bobSmith setFirstName:#"Bob"];
[bobSmith setLastName:#"Smith"]; // this is what I want to alphabetize it by
I have tried:
for (int i = 0; i < [nameArray count]; i++){
sortedNameArray = [[nameArray[i] getLastName] sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2){
return [(NSString *)obj1 compare:(NSString *)obj2 options:NSNumericSearch];
}];
}
but this obviously does not work. How can I get this method to alphabetize an array of objects by looking at one of it's string attributes.... ie taking an array of Name objects, looking at their last name (an NSString) and alphabetizing the objects according to this?
sortedNameArray = [nameArray sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
return [[obj1 lastName] compare:[obj2 lastName]];
}];
You can use sortDescriptors to alphabetise an array of Name objects
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"lastname" ascending:YES];
NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
NSArray *sortedArray = [nameArray sortedArrayUsingDescriptors:sortDescriptors];
nameArray =[NSMutableArray arrayWithArray:sortedArray];
I pulled the code from Sort Descriptor Programming Topics. Also, Key-Value Coding comes into play, in that sortedArrayUsingDescriptors: will send a valueForKey: to each element in myArray, and then use standard comparators to sort the returned values.
Related
This question already has answers here:
sort NSDictionary values by key alphabetical order
(4 answers)
Closed 6 years ago.
I have a dictionary in which, for a single key(for example key "0") there are a key value pair data.The keys are like name, id,p_id. I want to sort the NSMutableDictionary for the values related to the Key "name". The data in the dictionary is as follows,
0 = {
id = 12;
name = "Accounts ";
"p_id" = 13222071;
};
1 = {
id = 13;
name = "consultant";
"p_id" = 15121211;
};
2 = {
id = 11;
name = "Tania";
"p_id" = 10215921;
};
}
Any help is appreciated!
Please try out the below code:
[yourMutableArray sortUsingComparator: (NSComparator)^(NSDictionary *a, NSDictionary *b) {
NSString *key1 = [a objectForKey: #"name"];
NSString *key2 = [b objectForKey: #"name"];
return [key1 compare: key2];
}];
NSLog(#"Sorted Array By name key : %#", yourMutableArray);
Hope this helps!
NSArray *sortedKeys = [dict.allKeys sortedArrayUsingComparator:^NSComparisonResult(NSDictionary *d1, NSDictionary *d2) {
return [d1[#"name"] compare:d2[#"name"]];
}];
NSArray *objects = [dict objectsForKeys:sortedKeys notFoundMarker:[NSNull null]];
Dictionaries are not sorted, and doesn't resemble any order. What you should do is to getAll the keys first. Then apply a sort method on the keys, then request the objects according to the ordered keys.
E.g:
NSArray *keys = [dictionary allKeys];
NSArray *sortedKeys = <sort the keys according to your preferred method>
Now you can iterate the Dictionary from the order of the array sortedKeys.
While it has been made abundantly clear that Dictionaries can't be sorted and rightfully so, that does not mean the ends you are aiming for can't be achieved. This code will do that for you:
NSArray *arrayOfDicts = dic.allValues; //Now we got all the values. Each value itself is a dictionary so what we get here is an array of dictionaries
NSSortDescriptor *nameDescriptor = [[NSSortDescriptor alloc] initWithKey:#"name" ascending:YES]; //Create sort descriptor for key name
NSArray *sortingDesc = [NSArray arrayWithObject:nameDescriptor];
NSArray *sortedArray = [arrayOfDicts sortedArrayUsingDescriptors:sortingDesc]; //Get sorted array based on name
NSMutableDictionary *kindaSortedDict = [[NSMutableDictionary alloc] init];
int keyForDict=0;
for(NSDictionary *valDict in sortedArray)
{
[kindaSortedDict setObject:valDict forKey:[NSString stringWithFormat:#"%i",keyForDict]]; //Set values to our new dic which will be kind of sorted as the keys will be assigned to right objects
keyForDict++;
}
//Now you can simply get sorted array of keys from kindaSortedDic and results for them will always be sorted alphabetically. Alternatively you can just skip all that bother and directly use sortedArray
I have added comments in code to help you understand that.
For accessing sorted values I'd do this:
NSArray *sortedKeys = [kindaSortedDict.allKeys sortedArrayUsingDescriptors:
#[[NSSortDescriptor sortDescriptorWithKey:#"intValue"
ascending:YES]]];
for(NSString *key in sortedKeys)
{
NSDictionary *valDict = [kindaSortedDict objectForKey: key];
NSLog(#"Dict is: %# for key: %#",valDict,key);
}
I have a dictionary which contain this data:
(
contact={name="Lion",id="1",photo="simba.png",address="elm street"},
{name="Cat",id="2",photo="halleberry.png",address="attic"},
{name="Bat",id="3",photo="dracule.jpg",address="long way home baby"}
)
From that NSDictionary, i grab only the name and sorted it alphabetically. Like this:
(B={"Bat"}, C={"Cat"}, L={"Lion"})
This is the code i used:
NSMutableDictionary* sortedDict = [NSMutableDictionary dictionary];
for (NSDictionary* animal in dataDict[#"user"]){
NSString* name = animal[#"name"];
if (![name length])
continue;
NSRange range = [name rangeOfComposedCharacterSequenceAtIndex:0];
NSString* key = [[name substringWithRange:range] uppercaseString];
NSMutableArray* list = sortedDict[key];
if (!list){
list = [NSMutableArray array];
[sortedDict setObject:list forKey:key];
}
[list addObject:name];
Then, what i want to ask is. What i need to create an array of photos but sorted alphabetically based on the name. I mean something like this:
(B="dracule.jpg", C="halleberry.png"...etc)
I also heard that this will be more effective to use (B={name="Bat", photo="draggle.jpg"}) but don't know how i can make something like this and don't know how to call it separately. Please i need your help :"(
You can easily sort the array which contains dictionaries values, see below
//Get the contact array.
NSArray *contacts=[dic objectForKey:#"contact"];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"name" ascending:YES];
NSArray *sortedArray = [contacts sortedArrayUsingDescriptors:#[sortDescriptor]];
I hope it helps.
I have to sort an arrray according to configuration , Suppose its has some data of student which has student name
[NSArray arrayWithObjects:[NSDictionary dictionaryWithObjectsAndKeys:#"abc",#"name", nil],[NSDictionary dictionaryWithObjectsAndKeys:#"efg",#"name", nil][NSDictionary dictionaryWithObjectsAndKeys:#"cde",#"name", nil], nil];
and i have another array which say how to sort this array like its say first should be efg then abc and so on.
Is it possible using nsssortdescriptor or i have to write my custom code.
I would use a block to allow you to specify your comparison logic
NSArray *sortedArray = [_helpItems sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
return [(MAHelpItem *)a order] > [(MAHelpItem *)b order];
}];
self.items = sortedArray;
Perhaps this is what you're looking for:
NSArray *students;
NSArray *sortPriorities;
NSMutableArray *sortDescriptors = #[].mutableCopy;
for (NSString *key in sortPriorities) {
[sortDescriptors addObject:[NSSortDescriptor sortDescriptorWithKey:key ascending:YES]];
}
NSArray *sortedStudents = [students sortedArrayUsingDescriptors:sortDescriptors];
So I have an array of custom "Element" objects (hey hold atomic number, chemical symbol, atomic mass, etc...) and I am having trouble sorting them by one of their properties;
Here is the code:
switch (sortDescriptor) {
case 0: {
//Sort the array by "ATOMIC NUMBER"
NSArray *sortedArray = [self.elementsArray sortedArrayUsingComparator:^(id a, id b) {
NSNumber *first = #([(SAMElement *)a atomicNumber]);
NSNumber *second = #([(SAMElement *)b atomicNumber]);
return [first compare:second];
}];
self.elementsArray = [sortedArray mutableCopy];
}
case 1: {
//Sort the array by "ELEMENT NAME"
NSArray *sortedArray = [self.elementsArray sortedArrayUsingComparator:^(id a, id b) {
NSString *first = [(SAMElement *)a elementName];
NSString *second = [(SAMElement *)b elementName];
return [first compare:second];
}];
self.elementsArray = [sortedArray mutableCopy];
}
case 2:{
NSLog(#"sorting by chemical symbol");
//Sort the array by "CHEMICAL SYMBOL"
NSArray *sortedArray = [self.elementsArray sortedArrayUsingComparator:^(id a, id b) {
NSString *first = [(SAMElement *)a chemichalSymbol];
NSString *second = [(SAMElement *)b chemichalSymbol];
return [first compare:second];
}];
self.elementsArray = [sortedArray mutableCopy];
}
case 3: {
//Sort the array by "ATOMIC MASS"
NSArray *sortedArray = [self.elementsArray sortedArrayUsingComparator:^(id a, id b) {
NSNumber *first = [(SAMElement *)a atomicMass];
NSNumber *second = [(SAMElement *)b atomicMass];
return [first compare:second];
}];
self.elementsArray = [sortedArray mutableCopy];
}
default:
break;
}
When is sorts it returns a totally random list of elements. Am i doing something wrong?
The best way to sort an array of objects by some property of the object, its using NSSortDescriptor. In initWithKey, you can set the name of the property that you want to sort.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"atomicNumber" ascending:NO];
[self.elementsArray sortUsingDescriptors:#[sortDescriptor]];
In your case, just copy this code above in each case section of your switch statement, changing the key for #"elementName" and #"chemichalSymbol".
You can change the ascending value from NO to YES, depending what type of order do you want.
Please, let me know if worked or not.
I'm not seeing the bug immediately, but you're reinventing the wheel here. The correct tool for this is sortedArrayUsingDescriptors:
[self.elementsArray sortedArrayUsingDescriptors:#[
[NSSortDescriptor alloc] initWithKey:#"atomicNumber"] ascending:YES]
]];
Try that and see if it gets rid of your bug. If you're getting random orders, that usually suggests that your comparitor is inconsistent (sometimes A>B and sometimes B>A for the same A&B).
I have an NSMutableDictionary that maps NSString to NSString (although the values are NSStrings, they are really just integers).
For example consider the following mappings,
"dog" --> "4"
"cat" --> "3"
"turtle" --> "6"
I'd like to end up with the top 10 entries in the dictionary sorted by decreasing order of the value. Can someone show me code for this? Perhaps there is an array of keys and another array of values. However it is, I don't mind. I'm just trying to have it be efficient.
Thank you!
Get the Array of the Values, sort that array and then get the key corresponding to the value.
You can get the values with:
NSArray* values = [myDict allValues];
NSArray* sortedValues = [values sortedArrayUsingSelector:#selector(comparator)];
But, if the collection is as you show in your example, (I mean, you can infer the value from the key), you can always sort the keys instead messing with the values.
Using:
NSArray* sortedKeys = [myDict keysSortedByValueUsingSelector:#selector(comparator)];
The comparator is a message selector which is sent to the object you want to order.
If you want to order strings, then you should use a NSString comparator.
The NSString comparators are i.e.: caseInsensitiveCompare or localizedCaseInsensitiveCompare:.
If none of these are valid for you, you can call your own comparator function
[values sortedArrayUsingFunction:comparatorFunction context:nil]
Being comparatorFunction (from AppleDocumentation)
NSInteger intSort(id num1, id num2, void *context)
{
int v1 = [num1 intValue];
int v2 = [num2 intValue];
if (v1 < v2)
return NSOrderedAscending;
else if (v1 > v2)
return NSOrderedDescending;
else
return NSOrderedSame;
}
The simplest way is:
NSArray *sortedValues = [[yourDictionary allValues] sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)];
NSMutableDictionary *orderedDictionary=[[NSMutableDictionary alloc]init];
for(NSString *valor in sortedValues){
for(NSString *clave in [yourDictionary allKeys]){
if ([valor isEqualToString:[yourDictionary valueForKey:clave]]) {
[orderedDictionary setValue:valor forKey:clave];
}
}
}
Use this method:
- (NSArray *)sortKeysByIntValue:(NSDictionary *)dictionary {
NSArray *sortedKeys = [dictionary keysSortedByValueUsingComparator:^NSComparisonResult(id obj1, id obj2) {
int v1 = [obj1 intValue];
int v2 = [obj2 intValue];
if (v1 < v2)
return NSOrderedAscending;
else if (v1 > v2)
return NSOrderedDescending;
else
return NSOrderedSame;
}];
return sortedKeys;
}
Call it and then create a new dictionary with keys sorted by value:
NSDictionary *dictionary = [[NSDictionary alloc] initWithObjectsAndKeys:
#"4", #"dog",
#"3", #"cat",
#"6", #"turtle",
nil];
NSArray *sortedKeys = [self sortKeysByIntValue:dictionary];
NSMutableDictionary *sortedDictionary = [[NSMutableDictionary alloc] init];
for (NSString *key in sortedKeys){
[sortedDictionary setObject:dictionary[key] forKey:key];
}
Sorting the keys and using that to populate an array with the values:
NSArray *keys = [dict allKeys];
NSArray *sKeys = [keys sortedArrayUsingSelector:#selector(caseInsensitiveCompare:)];
NSMutableArray *sValues = [[[NSMutableArray alloc] init] autorelease];
for(id k in sKeys) {
id val = [dict objectForKey:k];
[sValues addObject:val];
}
NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:#"interest" ascending:YES];
[unsortedArray sortUsingDescriptors:[NSArray arrayWithObjects:descriptor,nil]];
recentSortedArray = [stories copy];
if you want to sort data in ascending order for key 'name' for such kind of Example then this may help you.
arrayAnimalList = [
{
'name' = Dog,
'animal_id' = 001
},
{
'name' = Rat,
'animal_id' = 002
},
{
'name' = Cat,
'animal_id' = 003
}
];
This is a code which help you to get sorted array
//here you have to pass key for which you want to sort data
NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:#"name" ascending:YES];
NSArray *sortDescriptors = [NSArray arrayWithObject:descriptor];
// here you will get sorted array in 'sortedArray'
NSMutableArray * sortedArray = [[arrayAnimalList sortedArrayUsingDescriptors:sortDescriptors] mutableCopy];