The question sounds weird but I'm getting an array of dictionaries as parsed result.
Something like this:
parsed content: (
{
"name" = "John";
"lastname" = "Doe";
"foo" = "bar";
}
What would be the suggestion for best way to create an array of values??
Like this?
- (void)flattenDictionary:(NSDictionary *)d intoKeys:(NSMutableArray *)keys andValues:(NSMutableArray *)values {
for (id key in [d allKeys]) {
[keys addObject:key];
[values addObject:[d valueForKey:key]];
}
}
- (void)flattenDictionaries:(NSArray *)arrayOfDictionaries {
NSMutableArray *keys = [NSMutableArray array];
NSMutableArray *values = [NSMutableArray array];
for (NSDictionary *d in arrayOfDictionaries) {
[self flattenDictionary intoKeys:keys andValues:values];
}
NSLog(#"now we have these values %#", values);
NSLog(#"corresponding to these keys %#", keys);
}
You can get the values with:
NSArray *values = dictionary.allValues;
Or, loop through it:
[dictionary enumerateKeysAndObjectsUsingBlock:^(id key, id object, BOOL *stop) {
NSLog(#"%# = %#", key, object);
}];
To do that loop through them and create an array.
Related
I have a NSMutableDictionary and I want to swap values & keys. i.e, after swapping values becomes keys and its corresponding keys with become values All keys and values are unique. Looking for an in place solution because size is very big . Also, the keys and values are NSString objects
NSMutableDictionary *d = [NSMutableDictionary dictionaryWithDictionary:#{
#"key1" : #"value1",
#"key2" : #"value2"}];
for (NSString *key in [d allKeys]) {
d[d[key]] = key;
[d removeObjectForKey:key];
}
NSLog(#"%#", d); // => { value1 : key1,
// value2 : key2 }
Assumptions
unique values (as they will become keys)
values conform to NSCopying (same as above)
no value is equal to any key (otherwise colliding names will be lost in the process)
Here is another way to invert dictionary. The simplest for me.
NSArray *keys = dictionary.allKeys;
NSArray *values = [dictionary objectsForKeys:keys notFoundMarker:[NSNull null]];
[dictionary removeAllObjects]; // In case of huge data sets release the contents.
NSDictionary *invertedDictionary = [NSDictionary dictionaryWithObjects:keys forKeys:values];
[dictionary setDictionary:invertedDictionary]; // In case you want to use the original dictionary.
EDIT: I had written a few lines of codes to get the OP started into the task of creating his own algorithm. The answer was not well received so I have crafted a full implementation of an algorithm that does what he asks, and goes one step further.
Advantages:
Makes no assumptions regarding the contents of the dictionary, for example, the values need not conform to the 'NSCopying' protocol
Transverses the whole hierarchy of a collection, swapping all the keys
It's fast since it uses recursion and fast enumeration
Does not alter the contents of the original dictionary, it creates a brand new one
Code has been implemented through categories to both collections:
#interface NSDictionary (Swapping)
- (NSDictionary *)dictionaryBySwappingKeyWithValue;
#end
#interface NSDictionary (Swapping)
- (NSDictionary *)dictionaryBySwappingKeyWithValue
{
NSMutableDictionary *mutableDictionary = [NSMutableDictionary dictionaryWithCapacity:self.count];
[self enumerateKeysAndObjectsUsingBlock:^(id key, id value, BOOL *stop) {
id newKey = nil;
if ([value isKindOfClass:[NSDictionary class]]) {
newKey = [value dictionaryBySwappingKeyWithValue];
} else if ([value isKindOfClass:[NSArray class]]) {
newKey = [value arrayBySwappingKeyWithValue];
} else {
newKey = value;
}
if (![newKey conformsToProtocol:#protocol(NSCopying)]) {
newKey = [NSValue valueWithNonretainedObject:newKey];
}
mutableDictionary[newKey] = key;
}];
return [NSDictionary dictionaryWithDictionary:mutableDictionary];
}
#end
and...
#interface NSArray (Swapping)
- (NSArray *)arrayBySwappingKeyWithValue;
#end
#implementation NSArray (Swapping)
- (NSArray *)arrayBySwappingKeyWithValue
{
NSMutableArray *mutableArray = [NSMutableArray arrayWithCapacity:self.count];
[self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
if ([obj isKindOfClass:[NSDictionary class]]) {
NSDictionary *newDict = [obj dictionaryBySwappingKeyWithValue];
mutableArray[idx] = newDict;
} else if ([obj isKindOfClass:[NSArray class]]) {
NSArray *newArray = [obj arrayBySwappingKeyWithValue];
mutableArray[idx] = newArray;
} else {
mutableArray[idx] = obj;
}
}];
return [NSArray arrayWithArray:mutableArray];
}
#end
As an example, assume you have a dictionary with the following structure:
UIView *view = [[UIView alloc] init];
NSDictionary *dict = #{#"1" : #"a",
#"2" : #[ #{ #"5" : #"b" } ],
#"3" : #{#"6" : #"c"},
#"7" : view};
NSDictionary *newDict = [dict dictionaryBySwappingKeyWithValue];
Printing the newDict object in the console will give you this output:
(lldb) po mutableDictionary
{
a = 1;
({b = 5;}) = 2;
{c = 6;} = 3;
"<30b50617>" = 7;
}
As you can see, not only have the keys and values been swapped at the first level of the hierarchy, but deep inside each collection.
"<30b50617>" represents the UIView object wrapped inside a NSValue. Since UIView does not comply to the NSCopying protocol, it needs to be handled this way if you want it to be a key in your collection.
Note: Code was done in a couple of minutes. Let me know if I missed something.
for (NSString *key in [myDictionary allKeys]) {
NSString *value = [responseDataDic objectForKey:key];
[myDictionary removeObjectForKey:key];
[myDictionary addObject:key forKey:value];
}
Assumption:
No key = value;
Complexity:
No extra space required. Will loop through once and replace all key value pairs.
NSArray* allKeys = [theDict allKeys];
NSArray* allValues = [theDict allValues];
NSMutableDictionary* newDict = [NSMutableDictionary dictionaryWithObjects:allKeys forKeys:allValues];
I've got an NSDictionary object like this:
dictionary: {
data = {
"access_token" = "xxx";
"expires_in" = 00;
"refresh_token" = "yyy";
"token_type" = bearer;
};
}
How can I flatten it so that I remove the 'data' object? Is there a quick way to do that?
So the output should look like this:
dictionary: {
"access_token" = "xxx";
"expires_in" = 00;
"refresh_token" = "yyy";
"token_type" = bearer;
};
NSDictionary *dataDict = [mainDict objectForKey:#"data"];
flat dict in your example:
//grab data
NSDictionary *data = [yourDict objectForKey:#"data"];
assert(data != nil);
NSDictionary *flatDict = data; //OR data.copy // OR [NSDictionary dictionaryWithDictionary:data];
It doesn't look like "data" is an NSDictionary. Try
id what = [dict objectForKey : #"data"];
NSLog(#"%#", [what class]);
What does it say?
using recursive function, the only problem with this method is it will replace the old data if key happened to be the same in the nested dictionary
- (NSDictionary *)flattedDictionary{
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
for (NSString *key in self.allKeys) {
id object = [self objectForKey:key];
if (![object isKindOfClass:[NSDictionary class]] && !isNull(object)) {
[dict setObject:object
forKey:key];
} else if ([object isKindOfClass:[NSDictionary class]]){
[dict addEntriesFromDictionary:[object flattedDictionary]];
}
}
return [NSDictionary dictionaryWithDictionary:dict];
}
I have an NSMutableArray that looks like this
{
"#active" = false;
"#name" = NAME1;
},
{
"#active" = false;
"#name" = NAME2;
}
Is there a way to convert this to an NSDictionary and then use objectForKey to get an array of the name objects? How else can I get these objects?
There is a even shorter form then this proposed by Hubert
NSArray *allNames = [array valueForKey:#"name"];
valueForKey: on NSArray returns a new array by sending valueForKey:givenKey to all it elements.
From the docs:
valueForKey:
Returns an array containing the results of invoking
valueForKey: using key on each of the array's objects.
- (id)valueForKey:(NSString *)key
Parameters
key The key to retrieve.
Return Value
The value of the retrieved key.
Discussion
The returned array contains NSNull elements for each object that returns nil.
Example:
NSArray *array = #[#{ #"active": #NO,#"name": #"Alice"},
#{ #"active": #NO,#"name": #"Bob"}];
NSLog(#"%#\n%#", array, [array valueForKey:#"name"]);
result:
(
{
active = 0;
name = Alice;
},
{
active = 0;
name = Bob;
}
)
(
Alice,
Bob
)
If you want to convert NSMutableArray to corresponding NSDictionary, just simply use mutableCopy
NSMutableArray *phone_list; //your Array
NSDictionary *dictionary = [[NSDictionary alloc] init];
dictionary = [phone_list mutableCopy];
This is an Array of Dictionary objects, so to get the values you would:
[[myArray objectAtIndex:0]valueForKey:#"name"]; //Replace index with the index you want and/or the key.
This is example one of the exmple get the emplyee list NSMutableArray and create NSMutableDictionary.......
NSMutableArray *emloyees = [[NSMutableArray alloc]initWithObjects:#"saman",#"Ruchira",#"Rukshan",#"ishan",#"Harsha",#"Ghihan",#"Lakmali",#"Dasuni", nil];
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
for (NSString *word in emloyees) {
NSString *firstLetter = [[word substringToIndex:1] uppercaseString];
letterList = [dict objectForKey:firstLetter];
if (!letterList) {
letterList = [NSMutableArray array];
[dict setObject:letterList forKey:firstLetter];
}
[letterList addObject:word];
} NSLog(#"dic %#",dict);
yes you can
see this example:
NSDictionary *responseDictionary = [[request responseString] JSONValue];
NSMutableArray *dict = [responseDictionary objectForKey:#"data"];
NSDictionary *entry = [dict objectAtIndex:0];
NSString *num = [entry objectForKey:#"num"];
NSString *name = [entry objectForKey:#"name"];
NSString *score = [entry objectForKey:#"score"];
im sorry if i can't elaborate much because i am also working on something
but i hope that can help you. :)
No, guys.... the problem is that you are stepping on the KeyValue Mechanism in cocoa.
KeyValueCoding specifies that the #count symbol can be used in a keyPath....
myArray.#count
SOOOOOO.... just switch to the ObjectForKey and your ok!
NSMutableDictionary *myDictionary = [NSMutableDictionary dictionaryWithObjectsAndKeys:#"theValue", #"#name", nil];
id kvoReturnedObject = [myDictionary valueForKey:#"#name"]; //WON'T WORK, the # symbol is special in the valueForKey
id dictionaryReturnedObject = [myDictionary objectForKey:#"#name"];
NSLog(#"object = %#", dictionaryReturnedObject);
Now I'm trying the following and it works.
- (void)findDictionaryWithValueForKey:(NSString *)name {
for (NSDictionary * set in myArray) {
if ([[set objectForKey:#"title"] isEqualToString:name])
\\do something
}
}
EDIT:
I've added one extra argument to the post of bshirley. Now it looks more flexible.
- (NSDictionary *)findDictionaryWithValue:(NSString*)name forKey:(NSString *)key {
__block BOOL found = NO;
__block NSDictionary *dict = nil;
[self.cardSetsArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
dict = (NSDictionary *)obj;
NSString *title = [dict valueForKey:key];
if ([title isEqualToString:name]) {
found = YES;
*stop = YES;
}
}];
if (found) {
return dict;
} else {
return nil;
}
}
Here's one possible implementation using newer API. (I also modified the method to actually return the value). Provided mostly to demonstrate that API. The assumption is that the title is unique to one dictionary within your array.
- (NSDictionary *)findDictionaryWithValueForKey:(NSString *)name {
// ivar: NSArray *myArray;
__block BOOL found = NO;
__block NSDictionary *dict = nil;
[myArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
dict = (NSDictionary *)obj;
NSString *title = [dict valueForKey:#"title"];
if ([title isEqualToString:name]) {
found = YES;
*stop = YES;
}
}];
if (found) {
return dict;
} else {
return nil;
}
}
Use filteredArrayUsingPredicate: method of the array to get all the dictionaries that satisfy your requirement.
NSPredicate * predicate = [NSPredicate predicateWithFormat:#" title MATCHES[cd] %#", name];
NSArray * matches = [myArray filteredArrayUsingPredicate:predicate];
Now matches is the array of dictionaries that have the title key equal to name.
- (void)findDictionaryWithValueForKey:(NSString)name {
for (NSDictionary * set in myArray) {
NSString *s=[NSString stringWithFormat:#"%#",[set objectForKey:#"title"]];
if ([s isEqualToString:name])
\\do something
}
OR
if (s == name])
\\do something
}
}
I will also suggest this way,it would be better if you use a break statement,
- (void)findDictionaryWithValueForKey:(NSString)name {
for (NSDictionary * set in myArray) {
if ([[set objectForKey:#"title"] isEqualToString:name])
\\do something
break;
}
}
As per the NSArray documentation,
valueForKey:
Returns an array containing the results of invoking valueForKey: using key on each of the array's objects.
- (id)valueForKey:(NSString *)key
Parameters
key
The key to retrieve.
Return Value
The value of the retrieved key.
Discussion
The returned array contains NSNull elements for each object that returns nil.
Availability
* Available in Mac OS X v10.3 and later.
EDIT:
try this,
[myArray valueForKey:#"name"];
//this will return array of values, but this actually differ from what to want
I have an NSArray of names, I want to sort them alphabetically into a UITableView and separate them into sections.
I have a tagged section at the top, being section 0. I want the names sorted aplhabetically to come after that. So all names beginning with A get put into section 1, B into section 2, and so on.
I need to be able to somehow get the number of rows for each section, and then put the objects in each section.
How do I do this?
Here is a method for a category on NSArray to do grouping:
#interface NSArray (Grouping)
- (NSArray*) groupUsingFunction: (id (*)(id, void*)) function context: (void*) context;
#end
#implementation NSArray (Grouping)
- (NSArray*) groupUsingFunction: (id (*)(id, void*)) function context: (void*) context
{
NSArray* groupedArray = nil;
NSMutableDictionary* dictionary = [NSMutableDictionary new];
if (dictionary != nil)
{
for (id item in self)
{
id key = function(item, context);
if (key != nil)
{
NSMutableArray* array = [dictionary objectForKey: key];
if (array == nil) {
array = [NSMutableArray arrayWithObject: item];
if (array != nil) {
[dictionary setObject: array forKey: key];
}
} else {
[array addObject: item];
}
}
}
groupedArray = [NSMutableArray arrayWithArray: [dictionary allValues]];
[dictionary release];
}
return groupedArray;
}
#end
You can use it like this:
id GroupNameByFirstLetter(NSString* object, void* context)
{
return [object substringToIndex: 1];
}
NSInteger SortGroupedNamesByFirstLetter(id left, id right, void* context)
{
return [[left objectAtIndex: 0] characterAtIndex: 0] - [[right objectAtIndex: 0] characterAtIndex: 0];
}
NSMutableArray* names = [NSArray arrayWithObjects: #"Stefan", #"John", #"Alex",
#"Sue", #"Aura", #"Mikki", #"Michael", #"Joe", #"Steve", #"Mac", #"Fred",
#"Faye", #"Paul", nil];
// Group the names and then sort the groups and the contents of the groups.
groupedNames_ = [[names groupUsingFunction: GroupNameByFirstLetter context: nil] retain];
[groupedNames_ sortUsingFunction: SortGroupedNamesByFirstLetter context: nil];
for (NSUInteger i = 0; i < [groupedNames_ count]; i++) {
[[groupedNames_ objectAtIndex: i] sortUsingSelector: #selector(compare:)];
}
I modified St3fans answer to be a bit more modern and work with Blocks instead:
#interface NSArray (Grouping)
- (NSArray*) groupUsingBlock:(NSString* (^)(id object)) block;
#end
- (NSArray*) groupUsingBlock:(NSString* (^)(id object)) block
{
NSArray* groupedArray = nil;
NSMutableDictionary* dictionary = [NSMutableDictionary new];
if (dictionary != nil)
{
for (id item in self)
{
id key = block(item);
if (key != nil)
{
NSMutableArray* array = [dictionary objectForKey: key];
if (array == nil) {
array = [NSMutableArray arrayWithObject: item];
if (array != nil) {
[dictionary setObject: array forKey: key];
}
} else {
[array addObject: item];
}
}
}
groupedArray = [NSMutableArray arrayWithArray: [dictionary allValues]];
[dictionary release];
}
return groupedArray;
}
You can use it like this:
NSArray *grouped = [arrayToGroup groupUsingBlock:^NSString *(id object) {
return [object valueForKey:#"name"];
}];
You should probably create an array of arrays, one for each letter, and store your names that way. While you can use a single array for storage, there's no quick way to do the segmentation you're looking for. Sorting, sure, but not section-ization.