I'm using the following code to convert a JSON string literal to an array holding an NSDictionary for each item:
NSString* json = #"[{\"name\":\"Item 1\",\"id\":\"999\",\"lang\":\"en\",\"type\":\"A\",\"version\":15}]";
NSData* data = [json dataUsingEncoding:NSUTF8StringEncoding];
NSArray* values = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
After removing the app from my test device, the app started crashing when attempting to access, in a for loop values[i][#"name"]. When viewing values in the inspector, I see the following:
values = (NSArray *) #"1 object"
[0] = (__NSDictionaryM *) 5 key/value pairs
[0] = (no summary) : #"Item 1"
[1] = #"id" : #"999"
[2] = #"type" : #"A"
[3] = (no summary) : (long)15
[4] = #"lang" : (no summary)
When expanded further, the keys that should be name and version are both shown to be the type (__NSCFConstantString *)
This was working prior to removing the app from the device, and no changes have been made to this section of the code.
Any ideas on what could be causing this, or better ways to convert the json string to a dictionary?
UPDATE: I changed "name" and "version" to "game" and "gersion", and it worked perfectly.
After attempting to debug this for several hours, my supervisor and I decided to restart the MacBook I'm developing on. This resolved the runtime issue, and the code in my question is once again working as expected.
We are still unsure what caused the device to get into this state, since running "Clean Build Folder" several times, closing and relaunching XCode, and restarting the iPad did nothing to help us.
I considered removing the question, but since we don't know what caused this I figured someone else may run into this issue in the future and this answer could help them. If anyone could provide some insight into what may have brought this situation about, I will gladly accept your answer.
Related
What I am trying to do is convert a document to an dictionary and then iterate that dictionary to see what's inside, but I am having the following problem when trying to convert the document.
I have the following code:
CBLDocument *document = row.value;
NSDictionary *dict = document.properties;
the xCode is always complaining "[__NSCFDictionary currentRevision]: unrecognized selector sent to instance 0x90c4150" when running to the second statement.
I have also tried NSDictionary *dict = document.currentRevision.properties;
It's not working either.
Could anyone help me with that?
OK, it turns out row.value is not a document(is actually a dictionary), but nobody tells me that when I emit(#[somekey], doc); The doc (which is the value) is actually a dictionary instead of a document.
But weird though the compiler did not complain when assigning the dictionary to a CBLDocument.
I have an NSMutableDictionary that loads data from a certain source.
He is loading fine and while debugging i am sure he is loading and that in the end he has the exact number of elements. I also can see the elements as they should while debugging.
I just want to get the value of the the row having the key value = 3 .
I tried NSString * myString = [myMutabDict objectForKey:#"3"], considering that the value is in string ,and i followed it with the debugger, and i am sure that my NSDictionary has elements in it , and i can see them while debugging, and i can see the key 3 , but i still get null as an output …
What am i missing?
If you are sure you see a value with a key of 3 and you can't load it using the key #"3" then it is possible that the key is a number. Use:
NSString *myString = [myMutableDict objectForKey:#3];
or modern syntax:
NSString *myString = myMutableDict[#3];
I have been attempting to debug a issue with my code, and just came upon an odd phenomenon. Found this in the debug area when a breakpoint was triggered:
Am I correct in observing that there are multiple values for this key: #"6898173"??
What are possible causes of this? I do not set those key-value pairs using the string literal, but by getting a substring of a string retrieved and decoded from a GKSession transmission.
I still have this up in the debug area in xcode, incase theres anything else there that might help.
EDIT:
By request, here is the code that would have created one of the two strings (another was created at an earlier time):
[carForPeerID setObject:[[MultiScreenRacerCarView alloc] initWithImage:[UIImage imageNamed:#"simple-travel-car-top_view"] trackNumber:[[[NSString stringWithUTF8String:data.bytes] substringWithRange:range] intValue]] forKey:[[NSString stringWithUTF8String:[data bytes]] substringFromIndex:9]];
The string in data might look something like this:
car00.0146898173
EDIT:
Code that sends the data:
[self.currentSession sendData:[[NSString stringWithFormat:#"car%i%#%#", [(MultiScreenRacerCarView *)[carForPeerID objectForKey:peerID] trackNumber], speed, [(MultiScreenRacerCarView *)[carForPeerID objectForKey:peerID] owner]] dataUsingEncoding:NSUTF8StringEncoding] toPeers:#[(NSString *)[peersInOrder objectAtIndex:(self.myOrderNumber + 1)]] withDataMode:GKSendDataReliable error:nil];
Sorry its hard to read. Its only one line.
What you're seeing is a debugger "feechure". When you have a mutable dictionary and modify it, the debugger may not show you the correct view of the object.
To reliably display the contents of an NSMutableArray or NSMutableDictionary, switch to the console and type po carForPeerID.
I'm building a project and want to add a NSNumber into a NSDictionary. But the it crashed because of the null value. So, I created another small program to check what happened. As you can see in the snapshot: Why the the value of NSNumber in NSDictionary is null?
I've run your code and I could reproduce the problem. But it seems like a debugger problem. For instance, if after your dictionary is created, go to the console and try printing the dictionary.
po dictionary
My result is like:
$4 = 0x2083e770 {
number = 1;
}
So it's not null at all. Also, after that, anum is assigned correctly and b is set to YES. So it really looks like a debugger issue instead of a bug from you.
I have a app that receive a feed from a server through json.
I have been building it for iOS5, but in the last weeks testing with iOS6. I tested today with a iOS5 device, and everything crashed.
The code looks like this:
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:#"http://www.myserver.com/news.json"]];
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
It worked without problems, but now it returns a null. The data is not null.
Cocoa error 3840 means
The data couldn’t be read because it has been corrupted. (No string
key for value in object around character 2.)
You should check your json with a validator like http://www.jsoneditoronline.org/ or http://jsonformatter.curiousconcept.com/
The issue was a duplicated key from the webserver. Now it works.
But it strange that the error is trigged in iOS5 and not in iOS6.