Retrieve data from firebase in objective c - ios

Question

I'm trying to retrieve data from firebase and I an using the guide given by firebase but I am not able to create the reference with my firebase database.
FIRDatabaseReference * ref = [[FIRDatabase alloc]
referenceFromURL:#"https://project-8326407164650950213.firebaseio.com"];
NSLog(#"%#",ref);
I am using this code to create the reference with my database but app crash.
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** setObjectForKey: key cannot be nil'
I am new in iOS and first time using firebase. Please tell me the solution as I am going according to firebase guide.

Answer 1

I'm no firebase expert, but when you're working with a class in Obj-C, you'll either invoke its class methods (e.g. [FIRDatabase database]), or you'll first allocate and initialize it ([[FIRDatabase alloc] <an initializer>]), and secondly use an instance method on the instance.
In your code sample above, I see an alloc without an initializer, which makes me think you're missing something.
If I look at the iOS quick start, I see a call to initWithURL, which is one of the initializers.

Answer 2

Firebase *messagePath = [[Firebase alloc] initWithUrl:[NSString stringWithFormat:#"%#%#%#", MAIN_URL,MESSAGES_DIRECTORY,conversationId]];
[[messagePath queryLimitedToLast:10] observeEventType:FEventTypeChildAdded withBlock:^(FDataSnapshot *snapshot) {
NSMutableArray *messages = [[NSMutableArray alloc] init];
[messages addObject:snapshot.value];
observingBlock(true,messages);
}];
Here is the code with you can get the data and value of the node. First make url till your node.
Still you have any problem just add comment here. now a days working on Firebase chat in swift.

Answer 3

You can do it easily. If you want to fetch all info using this you can do this. Make sure you have made your db public then no auth needed
#property (strong, nonatomic) FIRDatabaseReference *ref;
Define Property on interface then
self.ref = [[FIRDatabase database] reference];
[self.ref observeEventType:FIRDataEventTypeValue withBlock:^(FIRDataSnapshot * _Nonnull snapshot) {
NSDictionary *usersDict = snapshot.value;
NSLog(#"Information : %#",usersDict);
}];
If you want to fetch specific portion using this you can do this
[[self.ref child:#"results"] observeEventType:FIRDataEventTypeValue withBlock:^(FIRDataSnapshot * _Nonnull snapshot) {
NSDictionary *usersDict = snapshot.value;
NSLog(#"Info : %#",usersDict);
}];
My Fetched Json From Firebase
{
"results" : [
{
"name":"test 1",
"URL" : "URL STRING"
},
{
"name":"test 1",
"URL" : "URL STRING"
},
{
"name":"test 1",
"URL" : "URL STRING"
},
{
"name":"test 1",
"URL" : "URL STRING"
}
]
}