I am using following method to get back an NSDictionary object in ViewDidAppear. But when I attempt to access it in CellForRowAtIndexPath() it is always nil. I have tried adding an extra retain and copy to it, but it still gets released. I have been pulling my hair for 3 hours now. Any help would be appreciated.
Excerpt :
#property(nonatomic, retain) NSDictionary* userInfoObj;
- (void) viewDidAppear:(BOOL)animated
{
[super viewWillAppear:animated];
**//The object has data in it at this point**
self.UserInfoObj = [self getUserInfo];
}
- (NSDictionary*)getUserInfo
{
JsonHelper *helper=[[JsonHelper alloc] autorelease];
NSString* apiURL = [self.appDelegate urlGetUserInfo];
apiURL = [apiURL stringByReplacingOccurrencesOfString:#"{user_id}" withString:[UserSettings lastLoginUserId]];
return [helper getJsonDictionaryFromWebMethod:apiURL];
}
- (NSDictionary*)getJsonDictionaryFromWebMethod :(NSString*) url
{
.....
.....
....
// Get JSON as a NSString from NSData response
NSString *json_string = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];
// parse the JSON response into an object
// Here we're using NSArray since we're parsing an array of JSON status objects
dict = [[parser objectWithString:json_string error:nil] retain];
return dict;
}
Try putting self.UserInfoObj = [self getUserInfo]; in the viewDidLoad delegate method instead.
Related
In one of my methods, I fetched and parsed a JSON and placed it inside an NSArray called jsonArray in -(void)method1. I then copied the contents of that jsonArray to an NSMutableArray called copiedJsonArray to be used on other methods. Problem is, copiedJsonArray crashes whenever I log its contents in the console from the other methods -(void)method2 but it logs fine in -(void)method1.
How can I fix this?
In my header file:
#interface MainViewController : UIViewController
#property (nonatomic, retain) NSMutableArray *copiedJsonArray;
In my implementation file:
#synthesize copiedJsonArray;
- (void)viewDidLoad
{
[self method1];
}
- (void)method1
{
NSString *urlString = [NSString stringWithFormat:THE_URL];
NSURL *url = [NSURL URLWithString:urlString];
NSData *data = [NSData dataWithContentsOfURL:url];
NSString *jsonString = [[[NSString alloc] initWithData:data
encoding:NSUTF8StringEncoding] autorelease];
NSDictionary *jsonDictonary = [jsonString JSONValue];
NSArray *jsonArray = [jsonDictonary valueForKeyPath:#"QUERY.DATA"];
self.copiedJsonArray = [[NSMutableArray alloc] initWithArray:jsonArray copyItems:YES];
NSLog(#"Copied JSON Array in Method 1: %#", self.copiedJsonArray);
[self method2];
}
- (void)method2
{
NSLog(#"Copied JSON Array in Method 2: %#", self.copiedJsonArray);
}
I also tried doing this too but it does the same error:
copiedJsonArray = [jsonArray mutableCopy];
I also tried implementing NSCopy but fails too:
#interface MainViewController : UIViewController <NSCopying>
{
NSMutableArray *copiedJsonArray;
}
I'm doing this so that I can do a loop in my copiedJsonArray without fetching its contents from JSON again and again when the user taps on my UISegmentedControl.
If you call method2 before method1 it will crash as copiedJasonArray has not been created. You should not create instance variables inside methods (as you cannot know if they have been called). You should do it when you create your viewController, in viewDidLoad for example.
And use properties:
#interface
#property (retain) NSMutableArray* copiedJsonArray;
#end
then either
#synthesize copiedJsonArray = _copiedJsonArray
or leave that line it out (the compiler will put it in automatically in 4.5)
access as self.copiedJsonArray or _copiedJSONArray.
Outside of getters,setters,inits and deallocs, use the self. form, it's safer.
You could also create _copiedJsonArray lazily in the setter:
- (NSMutableArray*) copiedJsonArray
{
if (!_copiedJasonArray)
_copiedJsonArray = [NSMutableArray alloc] init;
return _copiedJasonArray;
}
I have the follow code that parses JSON data received from a server:
-(void)connectionDidFinishLoading:(NSURLConnection *)connection {
NSAutoreleasePool *pool=[[NSAutoreleasePool alloc] init];
NSArray *array_webdata=[[NSArray array] init];
NSString *searchStatus = [[NSString alloc] initWithData:webData encoding:NSUTF8StringEncoding];
array_webdata = [parsedata objectWithString:searchStatus error:nil];
NSDictionary *usersList = [array_webdata valueForKey:#"results"];
//I think that is not a real NSDictionary because if I write NSArray *keys = [usersList allKeys]; the execution crashes
NSLog(#"\n usersList =\n %# \n", usersList);
[searchStatus release];
[connection release];
[webData release];
[pool drain];}
the json data stored in usersList has the structure:
(
{
createTime = "date hour";
fullname = "user name";
"prof_id" = number;
thumb = "image.jpg";
},
{
data of rest of users...
}
)
And I would like create a class to store the data of each user and use "prof_id" when I want to use a particular use.
I need this because the app needs a list with all users (not tableview) and I think this is de easiest way.
Can someone help me? Thanks!!
Please used JsonKit Framework to parse json data received from web service.
Read data and parse using JSONKit:
NSData* jsonData = [NSData dataWithData:webData];
JSONDecoder* decoder = [[JSONDecoder alloc]
initWithParseOptions:JKParseOptionNone];
NSArray* json = [decoder objectWithData:jsonData];
After that, you'll have to iterate over the json variable using a for loop.
Create new class with the name User (file->new->file) inherited from NSObject class, create required parameters in .h/.m file.(do synthesize to generate getter/setter for attributes)
import User.h in your connection class and create objects of User entity in iterator loop and add those object in global scope array.
for(NSDictionary *userInfo in json) {
User* user=[[User alloc] init];
user.fullName=[userInfo valueForKey:#"fullname"];
user.prof_id=[[userInfo valueForKey:#"prof_id"] integerValue];
// Add into your global array
[usersList addObject:user];
[user release];// if ARC is not enable
}
// Check for successful object creation
NSLog(#"USER LIST contain User class Objects- %#",userList);
if i'm not wrong the only thing you need to do is :
NSMutableArray *yourArray = usersList;
and then with a for loop like
for(int i = 0;i<[usersList count] ;i++)
{
NSMutableDictionary *yourDictionary = [usersList objectAtIndex:i];
int prof_id = [yourDictionary valueForKey:#"prof_id"];
}
you can get your prof_id like that.
i hope this helps...
Use JSON Framework, and parse data using below code.
NSString* newStr = [[NSString alloc] initWithContentsOfURL:[NSURL URLWithString:#"yout link to json file"] encoding:NSUTF8StringEncoding error:nil];
NSLog(#"new str - %#",newStr);
NSArray *response = [newStr JSONValue];
NSLog(#"json array - %#",response);
Use the response array to show your results.
I want to fetch JSON data asynchronously. The data is set up in a way that one request will bring only 8 records. I need to send the requests repeatedly until the response becomes empty or returns less than 8 records.
Currently, I have these methods in myviewcontroller.m class:
(void)myCallback:(id)sender {
MyDataRequest *objMyDataRequest = [[[MyDataRequest alloc] init] autorelease];
objMyDataRequest.myRequiredVariableToGetAuthTokenDataResponse = classOfMyCallBack.someVariable;
// Initiate getAuthToken request
[objWishListRequest initiateGetAuthTokenRequest:self requestSelector:#selector(getAuthTokenDataResponse:)];
}
Now here is the definition of getAuthTokenDataResponse:
(void) getAuthTokenDataResponse:(NSData *)data {
NSString *stringResponse = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
SBJsonParser *parser=[[SBJsonParser alloc]init];
NSDictionary *objDictionaryForStringResponse = [parser objectWithString:stringResponse];
[stringResponse release];
[parser release];
MyListRequest *objMyListRequest = [[[MyListRequest alloc] init] autorelease];
objMyListRequest.myRequiredValueToGetMyDataResponse = [objDictionaryForStringResponse objectForKey:#"Data"];
// Initiate GetMyDataResponse request
[objMyListRequest initiateGetMyDataRequest:self requestSelector:#selector(getMyDataResponse:)];
}
(void) getMyDataResponse:(NSData *)data {
NSString *stringResponse = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
SBJsonParser *parser=[[SBJsonParser alloc]init];
NSDictionary *objGetMyDataRootDictionary = [parser objectWithString:stringResponse];
[stringResponse release];
[parser release];
NSDictionary *dataElements=[objGetMyDataRootDictionary objectForKey:#"Data"];
Wish *objMyData;
for (NSDictionary* objGetMyDataRootDictionary in dataElements) {
objMyData = [[Wish alloc]init];
//add different elements from dataElements into member variables of object objWish
[self.myDataArray addObject:objMyData];
[objMyData release];
}
[self.myDataTableView reloadData];
}
This method lies in MyDataRequest class:
(void)initiateGetMyDataRequest:(id)requestDelegate requestSelector:(SEL)requestSelector{
// Set the delegate and selector
self.delegate = requestDelegate;
self.callback = requestSelector;
NSString* unescapedUrlString = [NSString stringWithFormat:#"http://test.mytesturl.com/core.svc/alldata/My/get/All/?token=%#&search=&page=1",myRequiredtokenparameter];
[self request:url];
}
I need to send multiple requests to the same url (with different parameter value i.e. value of page number) to fetch the results. How may I achieve it given the above scenario? The calls must be asynchronous.
How should I make the actual flow between all these calls? How may I get the data of "all the pages" asynchronously?
I think you are looking for a operation queue. I use ASIHTTPRequests in my apps and they work.
If you want to use this library, here's the link how to use it: Show UIActivityIndicatorView when loading NSString from Web
I'm struggling to find the correct way to release an array after my method has been called. I wonder if there is a better way to achieve what I'm trying to acheive with my method:
- (NSArray *) setupDetailArray : (NSString *) selectedCategory {
// Load .plist file
NSString *path = [[NSBundle mainBundle] pathForResource:#"data" ofType:#"plist"];
// Load .plist into a new dictionary
NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:path];
// Drill down to next level
NSArray *faceSelection = [[NSArray alloc] initWithArray:[dict objectForKey:detailTitle]];
[dict release], dict = nil;
// Set up link to App Delegate
UltimateRageAppDelegate *dataCenter = (UltimateRageAppDelegate *) [[UIApplication sharedApplication] delegate];
dataCenter.faces = [[NSMutableArray alloc] init];
// Set app delegate faces to array
dataCenter.faces = faceSelection;
[dataCenter.faces release];
return faceSelection;
// [faceSelection release], faceSelection = nil; ??????
}
And I call my method in viewDidLoad
// If faceArray is empty, create it
if (faceArray == nil)
faceArray = [self setupDetailArray:detailTitle];
...
My application is leaking memory here, and I'm really looking for a way to release everything once I'm done.
Your method should return an autoreleased array which is then retained by the method that calls it if it wants/needs to keep it.
- (NSArray *) setupDetailArray : (NSString *) selectedCategory {
...
// Create the array, but don't own it
NSArray *faceSelection = [[[NSArray alloc] initWithArray:[dict objectForKey:detailTitle]] autorelease];
...
return facesSelected;
}
Now the code that calls this method should retain the object if it needs it. So, in your viewDidLoad
if (faceArray == nil)
faceArray = [[self setupDetailArray:detailTitle] retain];
...
If faceArray is an instance variable in your class, then you can just release it in your dealloc method.
You are also leaking memory here
// Set up link to App Delegate
UltimateRageAppDelegate *dataCenter = (UltimateRageAppDelegate *) [[UIApplication sharedApplication] delegate];
dataCenter.faces = [[NSMutableArray alloc] init];
// Set app delegate faces to array
dataCenter.faces = faceSelection;
[dataCenter.faces release];
This should be
// Set up link to App Delegate
UltimateRageAppDelegate *dataCenter = (UltimateRageAppDelegate *) [[UIApplication sharedApplication] delegate];
dataCenter.faces = faceSelection;
I'd suggest you read (and re-read and re-read) the docs on memory management and read up on properties, setters and the dot notation.
Apple Objective-C Memory Management
dataCenter.faces = [[NSMutableArray alloc] init];
You allocate a non-autoreleased array and assign it to the property faces (I bet it has the retain modifier).
dataCenter.faces = faceSelection;
Now you assign as new array to the faces property, but you haven't properly release the previous NSMutableArray.
[dataCenter.faces release];
You now indirectly release your faceSelection array.
You leak at least one NSMutableArray every time you run that method. You should do it like this instead:
// Drill down to next level
NSArray *faceSelection = [[dict objectForKey:detailTitle] copy];
[dict release], dict = nil;
// Set up link to App Delegate
UltimateRageAppDelegate *dataCenter = (UltimateRageAppDelegate *) [[UIApplication sharedApplication] delegate];
// Set app delegate faces to array
dataCenter.faces = faceSelection;
return [faceSelection autorelease];
Your method should return an autoreleased object. The only methods that should return retained objects are methods whose name:
starts with alloc
starts with new
contains copy
All other methods should return autoreleased objects.
Other way for doing this.
//Declare method as follows.
- (void) setupDetailArray : (NSString *) selectedCategory arrFaceArray:(NSArray *)faceArray
{
}
And I call my method in viewDidLoad
if (!faceArray)
{
faceArray = [[NSArray alloc] init]; //Alloc in ViewDidLoad and release in ViewDidUnload or dealloc.
faceArray = [self setupDetailArray:detailTitle arrFaceArray:faceArray];
}
Also consider the #DarkDust answer for maintaining autoreleased objects. Both are the possible ways.
I want to append 2 key values from JSON object to my list in iPhone app. Below is my code for that,
SBJsonParser *jsonParser = [[[SBJsonParser alloc] init] autorelease];
NSString *jsonString=[[NSString alloc] initWithContentsOfURL:[NSURL URLWithString:#"http://test/json/json_data.php"]];
id response = [jsonParser objectWithString:jsonString error:NULL];
NSDictionary *feed = (NSDictionary *)response;
list = (NSArray *)[feed valueForKey:#"fname"];
the above code properly displays the value from fname but what do i do if i want to add lname to it. for eg, my object is
[{"fname":"Bill","lname":"Jones"},{"fname":"John","lname":"Jacobs"}]
i want to display names as Bill Jones, John Jacobs and so on in the list. Currently it only displays Bill, John..I tried doing something like #"fname"#lname but it wont work..Can anybody please help me..
An observation: the response from the JSON parser is not a dictionary, but an array given the string you pass in. Your code works because -valueForKey: is something an array will respond to. The array sends -valueforKey: to each element and builds an array out of the responses.
There are two ways you can do what you want (at least)
Iterate through the array explicitly
NSMutableArray* list = [[NSMutableArray alloc] init];
for (id anObject in response)
{
[list addObject: [NSString stringWithFormat: #"%# %#",
[anObject objectForKey: #"fName"],
[anObject objectForKey: #"lname"]]];
}
Add a category to NSDictionary
#interface NSDictionary(FullName)
-(NSString*) fullName;
#end
#implementation NSDictionary(FullName)
-(NSString*) fullName
{
return [NSString stringWithFormat: #"%# %#",
[self objectForKey: #"fName"],
[self objectForKey: #"lname"]];
}
#end
Then your existing code changes to
list = (NSArray *)[feed valueForKey:#"fullName"];