iOS: App crashing, likely due to instantiation of class - ios

Question

I'm trying to debug a crash I'm experiencing...
I'm getting some data from a web server, so I've set up three classes:
Child
ChildConnection
ChildParser
ChildConnection contacts the web service and gets the data and starts the ChildParser, which then parse the xml and saves it as a Child object...
I've got it working in a project, where instead of having the ChildConnection, I set up the connection in the AppDelegate, and the issue I'm having in my current project is to do with delegates(at least that's what I think)... since I'm getting the error:
-[AppDelegate children]: unrecognized selector sent to instance 0x6b07e80
I'm fairly certain that the error is caused by: (NOTE: I'm pretty new to this)
- (ChildParser *) initChildParser {
self = [super init];
if(self)
{
childConnection = (ChildConnection *)[[UIApplication sharedApplication] delegate];
NSLog(#"Init");
}
return self;
}
ChildConnection.h:
#interface ChildConnection : NSObject
{
NSMutableArray *children;
NSMutableData *webData;
}
#property (nonatomic, retain) NSMutableArray *children;
-(void)connectionSetUp;
#end
ChildConnection.m:
#import "ChildConnection.h"
#import "ChildParser.h"
#implementation ChildConnection
#synthesize children;
- (void)connectionSetUp
{
NSString *soapMsg =
[NSString stringWithFormat:
Soap message left out due to sensitive data
];
NSURL *url = [NSURL URLWithString:#"Private"];
NSMutableURLRequest *req = [NSMutableURLRequest requestWithURL:url];
// Calculate the length of the post
NSString *postLength = [NSString stringWithFormat:#"%d", [soapMsg length]];
// Set the headers
[req addValue:postLength forHTTPHeaderField:#"Content-Length"];
[req addValue:#"text/xml; charset=utf-8" forHTTPHeaderField:#"Content-Type"];
[req addValue:#"PRIVATE" forHTTPHeaderField:#"SOAPAction"];
// Set the HTTP method and body
[req setHTTPMethod:#"POST"];
[req setHTTPBody:[soapMsg dataUsingEncoding:NSUTF8StringEncoding]];
NSURLConnection *myConnection = [[NSURLConnection alloc] initWithRequest:req delegate:self];
if(myConnection)
{
NSLog(#"Connection established");
webData = [NSMutableData data];
} else
{
NSLog(#"Connection failed");
}
}
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
NSLog(#"didReceiveResponse");
[webData setLength:0];
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
//NSLog(#"didReceiveData");
[webData appendData:data];
}
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
NSLog(#"didFailWithError: %#", [error localizedDescription]);
}
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSLog(#"Finished loading");
NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithData:webData];
//Initialize the delegate.
ChildParser *parser = [[ChildParser alloc] initXMLParser];
//Set delegate
[xmlParser setDelegate:parser];
//Start parsing the XML file.
BOOL success = [xmlParser parse];
/*
if(success)
NSLog(#"No Errors");
else
NSLog(#"Error Error Error!!!");
*/
//NSLog(#"Count: %#", [ count]);
}
#end
ChildParser.h:
#class Child;
#class ChildConnection;
#interface ChildParser : NSObject <NSXMLParserDelegate>
{
NSMutableString *currentElementValue;
Child *aChild;
ChildConnection *childConnection;
}
- (ChildParser *) initChildParser;
#end
.m:
#import "ChildParser.h"
#import "Child.h"
#import "ChildConnection.h"
#implementation ChildParser
- (ChildParser *) initChildParser {
self = [super init];
if(self)
{
childConnection = (ChildConnection *)[[UIApplication sharedApplication] delegate];
NSLog(#"Init");
}
return self;
}
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName
attributes:(NSDictionary *)attributeDict
{
NSLog(#"didstart");
if([elementName isEqualToString:#"GetKidsResult"])
{
// initialize the array
if(!childConnection.children)
{
childConnection.children = [[NSMutableArray alloc] init];
}
}
else if([elementName isEqualToString:#"a:KeyValueOfintKidf4KEWLbb"])
{
if(!aChild)
{
//Initialize the child.
aChild = [[Child alloc] init];
}
}
//NSLog(#"Processing Element: %#", elementName);
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
NSLog(#"foundcharacters");
/*
if(!currentElementValue)
{
currentElementValue = [[NSMutableString alloc] initWithString:string];
}
else
{
[currentElementValue appendString:string];
}*/
}
-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
//NSLog(#"El name: %#", elementName);
if([elementName isEqualToString:#"GetKidsResult"])
{
NSLog(#"end of xml");
return;
}
if([elementName isEqualToString:#"a:KeyValueOfintKidf4KEWLbb"])
{
//NSLog(#"Found end of child");
//[childConnection.children addObject:aChild];
//NSLog(#"added");
//int i = [childConnection.children count];
//NSLog(#"Count: %d", i);
//aChild = nil;
}
else if([elementName isEqualToString:#"a:Key"])
{
//NSLog(#"Found key: %#", currentElementValue);
//aChild.key = [currentElementValue intValue];
//NSLog(#"key: %#", aChild.key);
}
else if([elementName isEqualToString:#"b:CPR"])
{
//NSLog(#"Found cpr");
//aChild.cpr = [currentElementValue intValue];
}
else if([elementName isEqualToString:#"b:CheckedIn"])
{
//NSLog(#"Found checkedIn");
//aChild.checkedIn = [currentElementValue boolValue];
}
else if([elementName isEqualToString:#"b:FirstName"])
{
//NSLog(#"Found firstname: %#", currentElementValue);
//[aChild setValue:currentElementValue forKey:#"firstName"];
//aChild.firstName = currentElementValue;
}
else if([elementName isEqualToString:#"b:Gender"])
{
//NSLog(#"found gender");
//aChild.gender = currentElementValue;
}
else if([elementName isEqualToString:#"b:Id"])
{
//NSLog(#"found id");
aChild.idChild = [currentElementValue intValue];
}
else if([elementName isEqualToString:#"b:IsOnTour"])
{
//NSLog(#"found isontour");
//aChild.isOnTour = [currentElementValue boolValue];
}
else if([elementName isEqualToString:#"b:LastName"])
{
//NSLog(#"found lastname: %#", currentElementValue);
//aChild.lastName = currentElementValue;
}
else if([elementName isEqualToString:#"b:GroupName"])
{
//NSLog(#"found groupname");
//aChild.groupName = currentElementValue;
}
currentElementValue = nil;
}
- (void)parserDidEndDocument:(NSXMLParser *)parser
{
NSLog(#"didEndDocument");
//NSLog(#"Number of objects: %d", [childConnection.children count]);
[[NSNotificationCenter defaultCenter] postNotificationName:#"finishedParsing" object:nil];
}
#end
UPDATE
Okay, so got a bit further... I'm now getting a SIGABRT in the class where I use the data:
#import "AllView.h"
#import "CustomCellNoSubtitle.h"
#import "DTCustomColoredAccessory.h"
#import "Child.h"
#import "ChildConnection.h"
#implementation AllView
#synthesize allChildrenTable, childView, whichGroupLabel, charIndex;
-(void)receivedData
{
NSLog(#"data update gotten");
charIndex = [[NSMutableArray alloc] init];
listOfNames = [[NSMutableArray alloc] init];
for(int i=0; i<[childConnection.children count]-1; i++)
{
// get the person
Child *aChild = [childConnection.children objectAtIndex:i];
// get both first and last name and join them
NSString *joinName = [NSString stringWithFormat:#"%# %#", aChild.firstName, aChild.lastName];
// save the full name to an array of all the names
[listOfNames addObject:joinName];
// get the first letter of the first name
NSString *firstLetter = [aChild.firstName substringToIndex:1];
NSLog(#"first letter: %#", firstLetter);
// if the index doesn't contain the letter
if(![charIndex containsObject:firstLetter])
{
// then add it to the index
NSLog(#"adding: %#", firstLetter);
[charIndex addObject:firstLetter];
}
}
[allChildrenTable reloadData];
}
}
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// Deselect the row, so it's clear when the user returns
[allChildrenTable deselectRowAtIndexPath:indexPath animated:YES];
if(self.childView == nil)
{
ChildView *cView = [[ChildView alloc] initWithNibName:#"ChildView" bundle:[NSBundle mainBundle]];
self.childView = cView;
}
[self.navigationController pushViewController:childView animated:YES];
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// set the number of sections in the table to match the number of first letters
return [charIndex count];
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
// set the section title to the matching letter
return [charIndex objectAtIndex:section];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// get the letter in each section
NSString *alphabet = [charIndex objectAtIndex:section];
// get the names beginning with the letter
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF beginswith[c] %#", alphabet];
NSArray *names = [listOfNames filteredArrayUsingPredicate:predicate];
return [names count];
}
// set up an index
- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView
{
return charIndex;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
CustomCellNoSubtitle *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
//cell = [[CustomCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier];
//cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
cell = [[CustomCellNoSubtitle alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
//cell.frame = CGRectZero;
}
/*
//---get the letter in the current section---
NSString *alphabet = [charIndex objectAtIndex:[indexPath section]];
//---get all states beginning with the letter---
NSPredicate *predicate =
[NSPredicate predicateWithFormat:#"SELF beginswith[c] %#", alphabet];
NSArray *names = [listOfNames filteredArrayUsingPredicate:predicate];
if ([names count]>0) {
//---extract the relevant state from the states object---
NSString *cellValue = [names objectAtIndex:indexPath.row];
cell.primaryLabel.text = cellValue;
}
cell.myImageView.image = [UIImage imageNamed:#"kidblank.png"];*/
return cell;
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
//childConnection = (ChildConnection *)[[UIApplication sharedApplication] delegate];
childConnection =[[ChildConnection alloc] init];
[allChildrenTable reloadData];
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Set up a connection to the server to fetch the list of children
ChildConnection *childConnection = [[ChildConnection alloc] init];
[childConnection connectionSetUp];
// Set up a listener to receive notice when the parser is done
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(receivedData) name:#"finishedParsing" object:nil];
}

Answer 1

The problem looks pretty simple.
In your very first pasted function, you are assigning your app delegate to the variable childConnection.
childConnection = (ChildConnection *)[[UIApplication sharedApplication] delegate];
Surely you actually want to assign a new instance of the ChildConnection class to that property instead. Like this:
childConnection = [[ChildConnection alloc] init];
I know that Objective-C errors can sometimes be hard to make sense of, but the one you are getting is actually pretty clear:
[AppDelegate children]: unrecognised selector
So it's complaining that you are calling a method/property "children" on the app delegate. But why would you be calling anything on the app delegate if you aren't using it any more? And why would you call a method called "children" on it, when that's actually defined as a property of the ChildConnection class, not the app delegate?
Answer: because an object you thought was a ChildConnection is actually the app delegate.
UPDATE: It looks like you need to use the ChildConnection in more than one place. The easiest way to do this is to make a shared instance. Add this method to your ChildConnection class:
+ (ChildConnection *)sharedConnection
{
static ChildConnection *sharedConnection = nil;
if (sharedConnection == nil)
{
sharedConnection = [[self alloc] init];
}
return sharedConnection;
}
Now in your other classes, wherever you've used [[ChildConnection alloc] init] use [ChildConnection sharedInstance] instead.

Answer 2

Your right the offending piece of code is :
if(self)
{
childConnection = (ChildConnection *)[[UIApplication sharedApplication] delegate];
NSLog(#"Init");
}
And the reason why is your casting your AppDelegate to a ChildConnection Object, you can't do this because well it isn't a ChildConnection.
If you want to reference your childConnection in your AppDelegate i recommend the following:
+ (AppDelegate*)sharedDelegate;
//Implementation
+ (AppDelegate*)sharedDelegate {
return (AppDelegate*)[[UIApplication sharedApplication] delegate];
}
So this way you reference your childConnection like so:
[AppDelegate sharedDelegate].childConnection;
If you need data the moment the App starts initialise the childConnection in:
application:didFinishLaunchingWithOptions: