So, I am able to successfully perform a query of my parse database. This query matches the logged in user with all objects that have the logged in user in the key user. The object I'm querying has keys "email" "firstName" "lastName" "friendUserName" and "phoneNumber"
I would like to be able to store all the phone numbers into a mutable array named phoneNumbers. The code I am trying to use to do this is.
int i=0;
for (PFObject *object in objects) {
NSLog(#"%#", objects[i]);
phonenumber = object[#"phoneNumber"];
NSLog(#"%#", phonenumber);
[phoneNumbers[i] addObject:phonenumber];
NSLog(#"%#", phoneNumbers[i]);
i=i+1;
}
When I run this code the output for the code NSLog(#"%#", phoneNumbers[i]);
comes out a null both times. All other outputs are as expected.
The following should work for you:
NSMutableArray *phoneNumbers = [NSMutableArray new];
for (PFObject *object in objects) {
NSLog(#"%#", object);
// Assuming your phone numbers are stored as strings - use a different data type if necessary
NSString *phoneNumber = object[#"phoneNumber"];
NSLog(#"%#", phoneNumber);
[phoneNumbers addObject:phoneNumber];
}
NSLog(#"%#", phoneNumbers);
If you're just adding items to the end of a mutable array, you don't need to worry about the index of the items.
The place you were going wrong was when trying to add the object to your array. You were doing this:
[phoneNumbers[i] addObject:phonenumber];
Which is actually saying "fetch the object at index i in the phoneNumbers array, and tell it to add the phone number object". However, presumably your array is empty or not initialised, which means addObject will be sent to a nil object and so not have any effect. Instead, you simply need to tell the phoneNumbers array itself to add the object.
Related
I have recently moved to Realm from Coredata. In my app I am showing 50K + contacts .
The contact object is in the format:
Contact: firstName, lastName ,company
I am trying to fetch all the contacts in the Realm , and I am trying to display those contacts similar to the native contacts app in iPhone.
First I am creating the section header titles based on the contact first name:
-(NSArray *)getSectionTitleBasedOn:(NSString*)sortBy{
RLMResults *results = [self getMainDataSetFromRealm];
ContactSource *contactSource = results.firstObject;
NSMutableDictionary *nameDic = [NSMutableDictionary dictionary];
for (RealmContact *contact in contactSource.contacts){
if (contact.firstName.length>0) {
if ([sortBy isEqualToString:#"FirstName"]) {
[nameDic setObject:#"firstletter" forKey:[contact.firstName substringToIndex:1]];
}
}
}
NSLog(#"dic %#",nameDic);
return [[nameDic allKeys]sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)];
}
This gets me an array of letters which represent the title of section.
Now I am preparing the datasource for each section, so for section A, I am fetching all the contacts that begin with letter 'A'
-(void)prepareDataSource:(NSArray *)titleArr{
RLMResults *results = [self getMainDataSetFromRealm];
ContactSource *contactSource = results.firstObject;
__block NSMutableDictionary *dataSource = [NSMutableDictionary dictionary];
[titleArr enumerateObjectsUsingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
NSString *sectionHeader = obj;
RLMResults *contactResults = [contactSource.contacts objectsWhere:[NSString stringWithFormat:#"firstName BEGINSWITH '%#'",sectionHeader]];
NSMutableArray *contactRowArr = [NSMutableArray array];
for (Contact *contact in contactResults){
[contactRowArr addObject:contact];
}
[dataSource setObject:contactRowArr forKey:sectionHeader];
}];
_dataSource = [dataSource copy];
[self.tableView reloadData];
}
This works really well, but takes 3-5 seconds to load table which is fine but I am looking for ways to improve this data fetch .
Realm works on a principle of lazy-loading, where objects and their properties aren't loaded until you actually 'touch' them for the first time.
As a result, if you do any operations where you're manually iterating through all Realm objects in a results set at once, or manually copying specific objects to an array, you're going to incur a performance hit that will increase the more objects you persist in Realm.
The best way to minimize the performance hit is to try and mitigate how many times you iterate through the results sets and avoid copying objects out of the array as much as possible. RLMResults behaves like an array, so for most scenarios, you can usually just use that object instead.
In the prepareDataSource method, instead of looping through each object and passing them to that NSMutableArray, instead you could consider passing the RLMResults object itself instead.
The method getSectionTitleBasedOn: also seems quite inefficient since you're iterating through every single object in order to check if an entry with a particular first character exists. Instead, you could create an index of the alphabet, and then do a Realm query for entries that start with each letter, and then check to see if the resulting RLMResults object has a positive count (Though I'm not sure if this will actually be any faster).
But in the end, sometimes when you're doing complex sorting like this, where there's no 'clever' way to avoid iterating through each object in a database (Even Realm has to internally load each object when performing a sort), performance hits are unavoidable, in which case you should also make sure your UI has provisions to show a 'working' indicator to the user.
I have an array of NSDictionaries and i can access the values in them just fine but i am trying to filter these dictionaries down based on a user's search (user can only search by the dictionary key (#"uniqueSignName").
Once the user has searched through the names property i then need to display ALL dictionary associated data for that #"uniqueSignName" value.
I do the following code and always get the correct amount of NSLogs. For the life of me i cannot remember how to GET those dictionaries.
for (int i = 0; i < [filteredDictionaries count]; i++) {
if ([[[filteredDictionaries valueForKey:#"uniqueSignName"] objectAtIndex:i] isEqualToString:[self.filteredResults objectAtIndex:indexPath.row]]) {
NSLog(#"Power Rangers");
}
}
Eg: I search for "John"
NSLog: #"Power Rangers"
Correctly only appears once.
Now, how do i access another property of "John's" dictionary?
If you want to search the name then better way is that to use NPredicate without iterating the array.
Please see the below example..it may help you...
// Here array is your main array...
NSArray *filteredarray = [array filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"(uniqueSignName == %#)", #"John"]];
So the problem is solved, I can now access all the filtered properties.
for (NSDictionary *dict in filteredDictionaries) {
if ([[self.filteredResults objectAtIndex:indexPath.row] isEqualToString: dict[#"uniqueSignName"]]) {
NSString *myString = [NSString stringWithFormat:#"%#", dict[#"pType"]];
NSLog(#"hugh: %#", myString);
myString = displayPtype;
}
}
I have a dictionary with key-value pair populated from JSON returned data.What I wish to do is use the dictionary to populate UITableView.
I have this structure for table:
[Product Name]
By [Manufacturer Name]
What this means is that key is Product Name and Value is Manufacturer Name. I need to get the name of the key and the name of the value. How can this be done? and is it possible without for-loop?
I'd use the enumerateKeysAndObjectsUsingBlock: method. The following code builds a list of the strings you require.
NSMutableArray *names = [NSMutableArray array];
[dictionary enumerateKeysAndObjectsUsingBlock: ^(NSString *key, NSString *object, BOOL *stop) {
[names addObject[NSString stringWithFormat:#"%# By %#",key, object]];
}];
You can use the keyEnumerator of NSDictionary and for each key look up the value. This could look something like this:
for (NSString *p in dict)
{
NSString *m = [dict objectForKey:p];
// do something with (p,m)
}
You should not be concerned with avoiding for-loops. After all, something like a for loop will always happen somewhere underneath.
If your keys are dynamic from json then you can use
NSArray *keys = [dictionary allkeys];
Then in the table View Cell for row at index path method you can populate the table view with the corresponding keys and their values.
NSArray * keys = [results allKeys];
for (int i = 0;i<[keys count];c++){
NSString* productName = [key objectAtIndex:i];
NSString* manufacturerName = [results objectForKey:productName];
}
Hope this helps...
I have assumed the name as strings, you can change the type according to your situation..
I have a problem which I can't solve for a long time. I have a JSON response from the server which is parsed to NSDictionary lastMsgs as in the image below:
So for example 1323 it's a key and it associated with NSDictionary (which contains keys such as body, subject etc and values). So the problem I need in some way delete an entry which nested NSDictionary value has entry : type = 1. I don't know how to do this. I tried to do this:
NSMutableArray* _ModelVals = [[lastMsgs allValues] mutableCopy];
for (int i =0; i<[_ModelVals count]; i++) {
string_compare = [NSString stringWithFormat:#"%#" , [_ModelVals objectAtIndex:i]];
if ([string_compare rangeOfString:#"type = 1"].location != NSNotFound) {
[_ModelVals removeObjectAtIndex:i];
}
}
But it is work not correctly and delete not all entries which has type = 1. So the question - how can I implement this and delete entry in nested NSDictionary?
There is no value "type = 1" in the dictionary. That's just the log. You get the value of a key in a dictionary using [dict objectForKey:#"key"] or dict[#"key"].
Judging from your log, the type seems to be an NSNumber, not an NSString. Just get the int representation of it (assuming the type is an integer) and use a simple C int to int comparison.
And you can't filter an array like that. You will skip an entry. If you remove an entry, you have to decrease i by 1.
Or use this simpler solution:
NSSet *keys = [lastMsgs keysOfEntriesPassingTest:^BOOL(id key, id obj, BOOL *stop) {
return [obj[#"type"] intValue] == 1;
}];
NSMutableDictionary *dict = [lastMsgs mutableCopy];
[dict removeObjectsForKeys:[keys allObjects]];
This will first collect the keys of all objects (dictionaries) that have a type of 1 and then remove those from a mutable copy of the original dictionary.
You cannot add or remove objects from a collection while enumerating though it. I would create a another array that you can store references to the objects that you want to delete and remove them after you have looped though it.
I call an URL that returns me JSON (I use JSONKit). I convert it to a NSString that is this way:
[{"name":"aaaaaa","id":41},{"name":"as","id":23},...
And so on. I want to fill an UIPickerView with only the "name" part of the JSON. But, when the user selects a name, i need the "id" parameter, so i've thought to fill a NSDictionary with the JSON (setValue:id for key:name), so i can get the value picked by the user, and get the id from the dictionary. how could I fill an array with only the "name" of the JSON?
Im a bit lost with the JSONKit library, any guidance? Thank you.
First of all I don't think that its a good idea to have name as key in a dictionary, since you can have many identical names. I would go for id as key.
Now, what you could do is:
NSString *myJson; //Suppose that this is the json you have fetched from the url
id jsonObject = [myJson objectFromJSONString];
// Now you have an array of dictionaries
// each one having 2 key/value pairs (name/id)
NSArray *names = [jsonObject valueForKeyPath:#"name"];
NSArray *ids = [jsonObject valueForKeyPath:#"id"];
// Now you have two parallel arrays with names / ids
Or you could just iterate your json object and handle the data yourself:
for (id obj in jsonObject)
{
NSString *name = [obj valueForKey:#"name"];
NSNumber *id = [obj valueForKey:#"id"];
// Do whatever you like with these
}