I am trying to search a String in NSDictionary stored in NSMutableArray
for (int k = 0; k < [onlyActiveArr count]; k++) {
NSString *localID = [onlyActiveArr objectAtIndex:k];
NSLog(#"%#",localID);
int localIndex = [onlyActiveArr indexOfObject:localActiveCallID];
NSLog(#"%d",localIndex);
for (NSDictionary *dict in self.SummaryArr) {
NSLog(#"%#",[dict objectForKey:#"ActiveID"]);
if (![[dict objectForKey:#"ActiveID"] isEqualToString:localID]) {
NSLog(#"found such a key, e.g. %#",localID);
}
}
}
But I am getting
NSLog(#"found such a key, e.g. %#",localActiveCallID);
when the ID is still there in SummaryArr, I am checking if localID retrieved from onlyActiveArr is not present in dictionary.
Please suggest me how to overcome my problem.
You cannot make a decision that a key is not present until you finish processing the entire dictionary. Make a boolean variable initially set to NO, and change it to YES if you find an item in the dictionary, like this:
BOOL found = NO;
for (NSDictionary *dict in self.SummaryArr) {
NSLog(#"%#",[dict objectForKey:#"ActiveID"]);
found = [[dict objectForKey:#"ActiveID"] isEqualToString:localID];
if (found) break;
}
if (!found) {
NSLog(#"found such a key, e.g. %#",localID);
}
If you like predicates, then you can use the fact that accessing an inexistent key in a dictionary produces a nil value and make a predicate that filters out those dictionaries that have nil for your key.
If the count of the result is larger than zero, your key is somewhere in the array. It won't tell you where, though.
A snippet to show the idea:
NSPredicate *keyPred = [NSPredicate predicateWithFormat: #"NOT ActiveID == nil"];
BOOL found = [[self.SummaryArr filteredArrayUsingPredicate: keyPred] count] > 0;
I don't know how the performance stacks up, so if your data set is large you may want to check that the execution time is within your limits.
Related
I have NSDictionary with objects. The NSDictionary is consist of json(You can see it below). I need to populate my table view with the name by id. And the id can repeat. It means I can have several "name" with id which is equal 0. I should get name by key with certain value from the dictionary. Here is my NSDictionary:
{
name = "smth1";
id = 0;
},
{
name = "smth2";
id = 1;
},
{
name = "smth3";
id = 2;
},
{
name = "smth4";
id = 2;
},
...
For example, I want to get value of key "name" where id is 2. Then I will get name = "smth3" and name = "smth4". Generally, I am trying to populate my table view component with the nested data. How can I do this? Any tips, ideas. Thank you.
Actually you show an array of dictionaries, where each dictionary has 2 keys.
You could use the NSArray function indexOfObjectPassingTest. That code might look like this (starting from an NSArray) :
int idToFind = 2;
NSArray *dictArray = #[#{#"name": #"smth1",
#"id": #(0)},
#{#"name": #"smth2",
#"id": #(1)},
#{#"name": #"smth3",
#"id": #(2)}
];
NSUInteger dictIndex =
[dictArray indexOfObjectPassingTest: ^BOOL(
NSDictionary *dict,
NSUInteger idx,
BOOL *stop) {
return [dict[#"id"] intValue] == idToFind;
}];
if (dictIndex != NSNotFound) {
NSLog(#"Found id %d with name %#", idToFind, dictArray[dictIndex][#"name"]);
}
}
EDIT:
If you need to match all of the items then you need to use the NSArray method indexesOfObjectsPassingTest. That finds all the items in an array that match.
That code would look like this:
int idToFind = 2;
NSArray *dictArray = #[#{#"name": #"smth1",
#"id": #(0)},
#{#"name": #"Fred",
#"id": #(2)},
#{#"name": #"smth2",
#"id": #(1)},
#{#"name": #"smth3",
#"id": #(2)},
];
NSIndexSet *dictIndexes;
dictIndexes =
[dictArray indexesOfObjectsPassingTest: ^BOOL(NSDictionary *dict,
NSUInteger idx,
BOOL *stop)
{
return [dict[#"id"] intValue] == idToFind;
}];
if (dictIndexes.count == 0) {
NSLog(#"No matches found");
}
[dictIndexes enumerateIndexesUsingBlock:^(NSUInteger index,
BOOL * _Nonnull stop)
{
NSLog(#"Found id=%# with name \"%#\" at index %lu",
dictArray[index][#"id"],
dictArray[index][#"name"],
index);
}];
Both approaches above use methods that take a block. The block contains code that you write that returns a BOOL for the item(s) that match your desired search criteria.
Search/sort methods that take blocks are very flexible because you can provide any code you want to do the matching/comparison.
The indexOfObjectPassingTest method searches for a single object in your array and stops when it finds the first match.
In contrast, the indexesOfObjectsPassingTest function will match multiple items. It returns an NSIndexSet, a special class that's used to index into NSArrays.
There is a function enumerateIndexesUsingBlock that invokes a block of code for each index specified in the array.
We could also have used the method objectsAtIndexes to extract only the elements in the array that are listed in the resulting index set, and then used for...in to loop through the items. That code would look like this:
NSArray *filteredArray = [dictArray objectsAtIndexes: dictIndexes];
for (NSDictionary *aDict in filteredArray) {
NSLog(#"Found id=%# with name \"%#\"", aDict[#"id"], aDict[#"name"]);
}
Note that this sort of thing is simpler and cleaner in Swift. We could use a filter statement on the array and provide a closure that selects items that match our search criteria
I have an NSMutableDictionary with a structure like:
Main Dictionary > Unknown Dictionary > Dictionaries 1,2,4,5,6...
My question is what is the best way to retrieve the Unknown Dictionary key and set it as a variable? This is what I've tried:
NSEnumerator *enumerator = [myMutableDict keyEnumerator];
id aKey = nil;
while ( (aKey = [enumerator nextObject]) != nil) {
id value = [myMutableDict objectForKey:aKey]; // changed to `aKey`
NSLog(#"%#: %#", aKey, value); // tip via rmaddy
}
What goes into objectForKey: if you don't know the name of the object in the key?
The other thought I had was to populate an NSArray, then pulling each of the keys out somehow.
for (NSString *object in myMutableDict)
myArray = [myArray arrayByAddingObject:MainDict];
}
If anyone can suggest a better way to get the object (unknown) from an NSMutableDictionary I'm interested to learn.
You can enumerate dictionaries like this:
NSDictionary * someDictionary = ... however you set your dictionary;
[someDictionary enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
NSLog(#"Key: %#", key);
NSLog(#"Object: %#", obj);
}];
and set:
*stop = YES;
when you find the object you're looking for.
I'm not entirely sure if I understand your question correctly. I assume you have a "main" dictionary with exactly one (unknown) key that maps to another dictionary, which you want to retrieve. This would be a simple and concise way to do this:
NSDictionary *unknownDictionary = mainDictionary[mainDictionary.allKeys.firstObject];
(Yes, some people won't like the dot syntax here, but I find it easier to read in this case. You might also want to add some error checking, for the case that mainDictionary is empty etc.)
I've been trying to figure out a way of checking how many of a certain object are in an NSArray.
I've looked through the docs and I'm pretty sure there is no premade method for this. Also I can't find anything here on SO.
Do anybody know about a good way to do this? Because I seriously can't come up with anything.
In this specific case I have an array with strings (most cases several of each) and I want to count how many strings in the array that matches to whatever I ask for.
If this is a primary use of the data structure and order doesn't matter, consider switching to an NSCountedSet which is specifically for solving this problem efficiently.
If you need an ordered collection, and you don't have a huge set of objects, than the fast enumeration answers are the best approach.
If you want to know where the objects are, then use indexesOfObjectsPassingTest:.
If you have a huge number of object, I would look at indexesOfObjectsWithOptions:passingTest: with the NSEnumerationConcurrent option. This will allow you to search the array on multiple cores. (This is only possibly faster on a multi-core device, and even then is probably only faster if you have a very large collection. You should absolutely test before assuming that concurrent will be faster.) Even if you just need the final count, it may be faster for certain data sets to use this method and then use count on the final index set.
There actually is a method for this: - (NSIndexSet *)indexesOfObjectsPassingTest:(BOOL (^)(id obj, NSUInteger idx, BOOL *stop))predicate
NSIndexSet *indexes = [array indexesOfObjectsPassingTest:^(id obj, NSUInteger index, BOOL *stop) {
return [obj isEqualTo:myOtherObject];
}];
Sounds like a case for NSCountedSet, which does what you are after with its initWithArray: initializer:
// Example array of strings
NSArray *array = [NSArray arrayWithObjects:
#"Joe", #"Jane", #"Peter", #"Paul",
#"Joe", #"Peter", #"Paul",
#"Joe",
#"Jane", #"Peter",
nil];
NSCountedSet *countedSet = [[NSCountedSet alloc] initWithArray: array];
// for-in will let you loop over the counted set
for (NSString *str in countedSet) {
NSLog(#"Count of %#: %ld", str, (long)[countedSet countForObject:str]);
}
One approach would be to iterate and check.
- (int)repeatsOf:(NSString *)repeater inArray:(NSArray *)array {
int count = 0;
for (NSString *item in array) {
if ([item isEqualToString:repeater]) {
count++;
}
}
return count;
}
You could try a simple loop. Suppose needle is your reference string and array is your NSArray of strings:
unsigned int n = 0;
for (NSString * str in array)
{
if ([needle isEqualToString:str])
{
++n;
}
}
Now n holds the count of strings in equal to needle.
You could define a function like this:
- (int)countStringsThatMatch:(NSString*)match inArray:(NSArray*)array
{
int matches = 0;
for (id string in array) {
if ([string isEqualToString:match]) {
matches++;
}
}
return matches;
}
And then use it like:
int count = [self countStringsThatMatch:#"someString" inArray:someArray];
- (NSUInteger) objectCountInArray:(NSArray *)array
matchingString:(NSString *)stringToMatch {
NSUInteger count = 0;
for (NSString *string in array) {
count += [string isEqualToString:stringToMatch] ? 1 : 0;
}
return count;
}
You can try to expand this to use a block that gets an object and returns a BOOL. Then you can use it to compare an array of whatever you want.
I have array made from JSON response.
NSLog(#"%#", arrayFromString) gives the following:
{
meta = {
code = 200;
};
response = {
groups = (
{
items = (
{
categories = (
{
icon =
"http://foursquare.com/img/categories/parks_outdoors/default.png";
id = 4bf58dd8d48988d163941735;
and so on...
This code
NSArray *arr = [NSArray arrayWithObject:[arrayFromString valueForKeyPath:#"response.groups.items"]];
gives array with just one element that I cannot iterate through. But if I write it out using NSLog I can see all elements of it.
At the end I would like to have an array of items that I can iterate through to build a datasource for table view for my iPhone app.
How would I accomplish this?
EDIT:
I have resolved my issue by getting values from the nested array (objectAtIndex:0):
for(NSDictionary *ar in [[arrayFromString valueForKeyPath:#"response.groups.items"] objectAtIndex:0]) {
NSLog(#"Array: %#", [ar objectForKey:#"name"]);
}
First, the data structure you get back from the JSON parser is not an array but a dictionary: { key = value; ... } (curly braces).
Second, if you want to access a nested structure like the items, you need to use NSObject's valueForKeyPath: method. This will return an array of all items in your data structure:
NSLog(#"items: %#", [arrayFromString valueForKeyPath:#"response.groups.items"]);
Note that you will loose the notion of groups when retrieving the item objects like this.
Looking at the JSON string you posted, response.groups.items looks to be an array containing one item, a map/dictionary containing one key, "categories." Logging it out to a string is going to traverse the whole tree, but to access it programmatically, you have to walk the tree yourself. Without seeing a more complete example of the JSON, it's hard to say exactly what the right thing to do is here.
EDIT:
Traversing an object graph like this is not that simple; there are multiple different approaches (depth-first, breadth-first, etc,) so it's not necessarily something for which there's going to be a simple API for you to use. I'm not sure if this is the same JSON library that you're using, but, for instance, this is the code from a JSON library that does the work of generating the string that you're seeing. As you can see, it's a bit involved -- certainly not a one-liner or anything.
You could try this, which I present without testing or warranty:
void __Traverse(id object, NSUInteger depth)
{
NSMutableString* indent = [NSMutableString string];
for (NSUInteger i = 0; i < depth; i++) [indent appendString: #"\t"];
id nextObject = nil;
if ([object isKindOfClass: [NSDictionary class]])
{
NSLog(#"%#Dictionary {", indent);
NSEnumerator* keys = [(NSDictionary*)object keyEnumerator];
while (nextObject = [keys nextObject])
{
NSLog(#"%#\tKey: %# Value: ", indent, nextObject);
__Traverse([(NSDictionary*)object objectForKey: nextObject], depth+1);
}
NSLog(#"%#}", indent);
}
else if ([object isKindOfClass: [NSArray class]])
{
NSEnumerator* objects = [(NSArray*)object objectEnumerator];
NSLog(#"%#Array (", indent);
while (nextObject = [objects nextObject])
{
__Traverse(nextObject, depth+1);
}
NSLog(#"%#)", indent);
}
else
{
NSLog(#"%#%#",indent, object);
}
}
void Traverse(id object)
{
__Traverse(object, 0);
}
I need to pick string valur from an NSMutableArray then save it into a plist. I've builded an NSMutableArray to display infos in table View. Maximum allowed index is 8. (paste just two in example)
The problem if the String doesn't exist, I get the following error:
sDict is a dictionary for saving datas to a property list file.
the code:
- (IBAction)save:(id)sender {
(...)
NSString *One;
NSString *Two;
...etc
if ([self.smOne objectAtIndex:0])
One = [self.smOne objectAtIndex:0];
if ([self.smOne objectAtIndex:1])
Two = [self.smOne objectAtIndex:1];
...etc
if (One)
[sDict setObject:[self.smTwo objectAtIndex:0]
forKey:[UserM stringByAppendingString:One]];
[sDict setObject:[self.smThree objectAtIndex:0]
forKey:[UserS stringByAppendingString:One]];
[sDict setObject:[self.smFour objectAtIndex:0]
forKey:[UserP stringByAppendingString:One]];
if (Two)
[sDict setObject:[self.smTwo objectAtIndex:1]
forKey:[UserM stringByAppendingString:Two]];
[sDict setObject:[self.smThree objectAtIndex:1]
forKey:[UserS stringByAppendingString:Two]];
[sDict setObject:[self.smFour objectAtIndex:1]
forKey:[UserParM stringByAppendingString:Two]];
...etc
}
This code works if all objects are present, but fails if it miss one of the object at index.
I really don't know how to check properly if the object is present or not, cause code above seem's to don't works well.
I've tried with [self.smOne count] but as problem to pass as a Int or String to make conditions with.
Thanks for answer.
it looks like you're explicitly checking smOne from indices 1 through 8. But you also mentioned that the array can have up to 8. So if it's missing, say, 6, 7 and 8, you'd still be calling [smOne objectAtIndex:6], which would result in an NSRangeException being raised as 6 is out of bounds for the array.
try this instead:
int i = 0;
for ( NSString *aString in self.smOne )
{
[sDict setObject:[self.smTwo objectAtIndex:i]
forKey:[UserM stringByAppendingSting:aString]];
[sDict setObject:[self.smThree objectAtIndex:i]
forKey:[UserS stringByAppendingString:aString]];
[sDict setObject:[self.smFour objectAtIndex:i]
forKey:[UserP stringByAppendingString:aString]];
i++;
}
it'll go through each object in the smOne array and add the object into sDict regardless of how many items you have in smOne.
also, be careful with how you're generating your keys. there's the possibility that [UserM stringByAppendingSting:aString] won't always be unique.
Sorry to ask again but i have dificulties to find how to rebuild arrays from the key/string couple saved with the loop.
i've tried this:
int i = 0;
for (NSString *SMServ in [temp objectForKey:
[UserMen stringByAppendingFormat:#"%d",i]]){
NSString *SMMem[i];
SMMem[i] = [temp objectForKey:[UserMen stringByAppendingFormat:#"%d",i]];
NSArray *theArray = [ NSArray arrayWithObjects:SMMem count:i];
i++;
}
But nothing happens.
if i try with for (i = 0; i < 9; i ++) and (i + 1) instead of [i], i get same bounds errors in the first example.
thanks again for help.
Well, finally it ,works. Thanks for link to the documentation, i read too fast last time.
I'm sure this is not the cleanest way, but it works with this loop:
for (key in sDict) {
if ([sDict valueForKey:[UserMen stringByAppendingFormat:#"%d",i]]) {
tempMe = [sDict valueForKey:[UserMen stringByAppendingFormat:#"%d",i]];
if (tempMe) {
[manArray insertObject:tempMe atIndex:(0 + a)];
[bankArray insertObject:[NSString stringWithFormat:#"%d",i] atIndex:(0 + a)];
a++;
}
}
if ([sDict valueForKey:[UserSerial stringByAppendingFormat:#"%d",i]]) {
SMSer = [sDict valueForKey:[UserSerial stringByAppendingFormat:#"%d",i]];
if (SMSer) {
[serArray insertObject:SMSer atIndex:(0 + b)];
b++;
}
}
if ([sDict valueForKey:[UserPart stringByAppendingFormat:#"%d",i]]) {
SMPart = [sDict valueForKey:[UserPart stringByAppendingFormat:#"%d",i]];
if (SMPart) {
[partArray insertObject:SMPart atIndex:(0 + c)];
c++;
}
}
i++;
}