Im currently devising a solution for my object BuildingNode *tower which is held inside NSMutableArray *gameObjects, to attack EnemyNode *enemy objects also held inside the gameObjects array.
I have a proposed solution which occasionally causes my game to freeze (temporarily) as the solution employed is quite buggy.
My solution is that each tower object contains its own NSMutableArray *targets which is synthesized from the Tower Class. If an enemy comes into range or out of range of any given tower object, the corrosponding index of the EnemyNode *enemy object from the gameObjects array is saved as an NSNumber into the targets array, or alternatively if the enemy object is out of range, it is removed from the .targets array.
Basically the idea is that the targets array holds the indices of any enemy that is in scope of the tower.
The problem I seem to be facing is that because this tower.targets array is updated dynamically all the time, i believe that if i'm doing some sort of operation on a particular index of tower.targets that then is removed, i get this error:
-[BuildingNode distance]: unrecognized selector sent to instance 0x2dd140
Each BuildingNode *tower has different attacking alogrithms that use the tower.targets array for calling back the sorted/desired enemy.
For example, a random attack style will randomize a number between 0 & [tower.targets count] then I can create a pointer to gameObjects with the corresponding [tower.targets intValue].
Something like this:
EnemyNode *enemy = (EnemyNode *)[gameObjects objectAtIndex:[[tower.targets objectAtIndex:rand]intValue]];
So this will find a random enemy from the potential .targets array and then create a pointer object to an enemy.
I've put in many if statements to ensure that in the case of a .targets index being removed mid-sorting, the operation shouldnt go ahead, thus removing the game failure rate, but it still occurs occassionally.
Heres my code:
Please note that BuildingNode *tower == BuildingNode *build.
This is just a snippet of the iteration inside gameObjects.
//Potential Enemies (Indices) Add and Delete/
if (enemy.distance < build.atk_distance && !enemy.isExploding){
NSNumber *index = [NSNumber numberWithInt:[array indexOfObject:enemy]];
if(![build.targets containsObject:index]){
[build.targets addObject:index];
}
}
else {
NSNumber *index = [NSNumber numberWithInt:[array indexOfObject:enemy]];
if ([build.targets containsObject:index]){
[build.targets removeObject:index];
}
}
}
//Aiming// Nearest Algorithm.
//Will find the nearest enemy to the building
if (enemy.distance < build.atk_distance){
if (!build.isAttacking || build.atk_id == 0){
if ([build.targets count]){
if ([build.atk_style isEqualToString:#"near"]){
int l_dist;
for (int i = 0; i < [build.targets count]; i++){
//Grab the Enemy from Targets
if ([build.targets objectAtIndex:i]){
if([array objectAtIndex:[[build.targets objectAtIndex:i]intValue]]){
EnemyNode *temp = [array objectAtIndex:[[build.targets objectAtIndex:i]intValue]];
if (temp){
int c_dist = temp.distance;
if (!l_dist || c_dist < l_dist){
l_dist = c_dist;
build.atk_id = temp.uniqueID;
build.isAttacking = YES;
}
}
}
}
}
}
}}
Unrecognized selector sent = calling a method on an object that doesn't exist. In this case, you're calling the distance method/property getter on a BuildingNode object.
The only distance I see is on your temp object, which is retrieved by EnemyNode *temp = [array objectAtIndex:[[build.targets objectAtIndex:i]intValue]]; That indicates you are really pulling a BuildingNode object out of the array instead of an EnemyNode. Find out why that happens.
Related
So I pulled some JSON data from a web service which is stored in an NSArray called _infoFromJSON. Each array element in _infoFromJSON essentially has a dictionary of key/value pairs. The goal is to add them to myVehicleObject which is an NSMutableArray
for (NSDictionary* myDictionary in _infoFromJSON) {
myVehicleObject *vehicleInMembersProfile;
vehicleInMembersProfile = [[myVehicleObject alloc] init];
vehicleInMembersProfile.make = [[_infoFromJSON objectAtIndex:carCount] objectForKey:#"make"];
vehicleInMembersProfile.carName = [[_infoFromJSON objectAtIndex:carCount] objectForKey:#"nickname"];
vehicleInMembersProfile.year = [[_infoFromJSON objectAtIndex:carCount] objectForKey:#"year"];
carCount ++;
[self.myVehicleObject addObject:vehicleInMembersProfile] ;
};
With the above code I sort of achieved it, however it keeps adding the same 1st dictionary to myVehicleObject, so it inserts the same NSDictionary 4 times In the past I have used this:
[self.myVehicleObject addObject:[vehicleInMembersProfile copy]] ;
When I do it it throws the following exception:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[myVehicleObject copyWithZone:]: unrecognized selector sent to instance 0xab4e130'
What am I doing wrong here? Thanks!
Update Requested Sample JSON:
{
color = SILVER;
engine = "";
id = "CF270B81-3821-4585-8C90-7089D7A8654E";
imageUrl = "https://www.someprotectedurl.com/somefile.png";
licensePlate = "ABC-123";
make = Honda;
model = "CR-V";
nickname = "My CR-V";
vin = "XX551234687687687654";
year = 2009;
}
This may or may not be related to the problem, but your forin loop is completely broken. Whether or not your incorrect usage is the actual cause of the problem, this is something you should definitely fix as it can do nothing but cause problems.
If you want to use indexOfObject: to grab an object at an index of the array you're iterating through, you should use a regular for loop:
for (int carCount=0; index < [_infoFromJSON count]; ++carCount) {
// loop body remains identical to what you have...
// except remove carCount++;
}
But for what you're doing, a forin loop is indeed better, and forin loops can be faster since they can be handled in batches. But if you're using a forin loop, use the object you're defining in the loop declaration:
for(NSDictionary* myDictionary in _infoFromJSON) {
// myDictionary is a reference to an object in _infoFromJSON,
//for whatever given index it is currently working on
myVehicleObject *vehicleInMembersProfile = [[myVehicleObject alloc] init];
vehicleInMembersProfile.make = myDictionary[#"make"];
vehicleInMembersProfile.carName = myDictionary[#"nickname"];
vehicleInMembersProfile.year = myDictionary[#"year"];
[self.myVehicleObject addObject:vehicleInMembersProfile];
}
The error is that your class does not implement NSCopying.
However, there isn't any need to copy the object here. You're creating a new object each time through the loop. If you insert a copy, you're just pointlessly throwing away the original each time. The more likely cause if you're seeing odd loop behavior is that your loop is mixing up different kinds of enumeration, as pointed out by nhgrif. Instead of accessing [_infoFromJSON objectAtIndex:carCount], just use myDictionary.
I would probably use a for loop rather than a foreach since you need the array index, I would code it like this
NSMutableArray *vehiclesArray = [[NSMutableArray alloc]init];
for (int i = 0; i < [_infoFromJSON count]; i++)
{
//create vehicle
myVehicleObject *vehicleInMembersProfile = [[myVehicleObject alloc] init];
vehicleInMembersProfile.make = _infoFromJSON[i][#"make"];
vehicleInMembersProfile.carName = _infoFromJSON[i][#"nickname"];
vehicleInMembersProfile.year = _infoFromJSON[i][#"year"];
//finally add the vehicle to the array
[vehiclesArray addObject:vehicleInMembersProfile] ;
}
I wasn't sure what myVehicleObject was , and why is it the same type you are adding to itself, so I changed it to an array. But you get the point.
I have an issue that (I think) might have to do with scope, but I'm not sure. I'm trying to do something that I think should be simple, but I am getting a strange result, and I could truly use some advice. I would say I'm an early-objective-c programmer, but not a complete newb.
I have written a function in objective-c that I would like to use to change the key-names in a mutable array of mutable dictionary objects. So, I want to pass in a mutable array of mutable dictionary objects, and return the same mutable array with the same dictionary objects, but with some of the key-names changed. Make sense?
I have tried several log statements in this code, which seem to indicate that everything I'm doing is working, except when the for loop is finished executing (when I try to test the values in the temp array), the array appears to contain only the LAST element in the source array, repeated [source count] times. Normally, this would lead me to believe I'm not writing the new values correctly, or not reading them correctly, or even that my NSLog statements aren't showing me what I think they are. But might this be because of scope? Does the array not retain its changes outside of the for loop?
I have put a fair amount of time into this function, and I have exhausted my bag of tricks. Can anyone help out?
-(NSMutableArray *)renameKeysIn:(NSMutableArray*)source {
/*
// Pre:
// The source array is an array of dictionary items.
// This method renames some of the keys in the dictionary elements, to make sorting easier later.
// - "source" is input, method returns a mutable array
*/
// copy of the source array
NSMutableArray *temp = [source mutableCopy];
// a temporary dictionary object:
NSMutableDictionary * dict = [[NSMutableDictionary alloc] init];
// These arrays are the old field names and the new names
NSMutableArray *originalField = [NSMutableArray arrayWithObjects:#"text", #"created_at",nil];
NSMutableArray *replacedField = [NSMutableArray arrayWithObjects:#"title", #"pubDate", nil];
// loop through the whole array
for (int x =0; x<[temp count]; x++) {
// set the temp dictionary to current element
[dict setDictionary:[temp objectAtIndex:x]];
// loop through the number of keys (fields) we want to replace (created_at, text)... defined in the "originalField" array
for (int i=0; i<[originalField count]; i++)
{
// look through the NSDictionary item (fields in the key list)
// if a key name in the dictionary matches one of the ones to be replaced, then replace it with the new one
if ([dict objectForKey:[originalField objectAtIndex:i]] != nil) {
// add a new key/val pair: the new key *name*, and the old key *value*
[dict setObject:[dict objectForKey:[originalField objectAtIndex:i]]
forKey:[replacedField objectAtIndex:i]];
// remove the old key/value pair
[dict removeObjectForKey:[originalField objectAtIndex:i]];
}// end if dictionary item not null
}// end loop through keys (created_at, text)
[temp replaceObjectAtIndex:x withObject:dict];
}// end loop through array
// check array contents
for (int a=0; a<[temp count]; a++){
NSLog(#"Temp contents: ############ %#",[[temp objectAtIndex:a] objectForKey:#"pubDate"]);
}
return temp;
} // end METHOD
I think the issue is on the line with:
[dict setDictionary:[temp objectAtIndex:x]];
Since these things are almost all working in pointers (instead of copying contents), every element of your temp array will point to the dict dictionary, which is set to be whatever the latest key's dictionary is. I think setting the actual pointer will fix the issue.
dict = [temp objectAtIndex:x];
I can grab a random value from an array-like structure by retrieving a random index.
How can I grab a random value from an NSSet object that stores NSNumber objects? I couldn't find an instance method of NSSet that retrieves a random value.
In short, you can't directly retrieve a random object from an NSSet.
You either need to turn the set into an array -- into something that has an index that can be randomized -- by re-architecting your code to use an array or you could implement this using this bit of pseudo-code:
randomIndex = ...random-generator....(0 .. [set count]);
__block currentIndex = 0;
__block selectedObj = nil;
[set enumerateObjectsWithOptions:^(id obj, BOOL *stop) {
if (randomIndex == currentIndex) { selectedObj = obj; *stop = YES }
else currentIndex++;
}];
return selectedObj;
Yes -- it iterates the set, potentially the whole set, when grabbing the object. However, that iteration is pretty much what'll happen in the conversion to an NSArray anyway. As long as the set isn't that big and you aren't calling it that often, no big deal.
Whilst I like that #bbum answer will terminate early on some occasions due to the use of stop in the enumeration block.
For readability and ease of remembering what is going on when you revisit this code in the future I would go with his first suggestion of turn the set into an array
NSInteger randomIndex = ..random-generator....(0 .. [set count])
id obj = [set count] > 0 ? [[set allObjects] objectAtIndex:randomIndex] : nil;
I have a very strange error using NSMutableArray in cocos2d/xcode
In my code, I have a NSMutableArray containing object A
NSMutableArray *peasantArray;
and another NSMutableArray contain object B
NSMutableArray *treeArray;
in the scheduled update function, I called another function which is essentially the following functionality:
I would loop through all the object A inside the *peasantArray, and if any peasant object has a variable var == GameEntityCommandIdling, I would modify the object B in the second NSMutableArray *treeArray,
The issue is that I notice sometimes after I modified the object A inside the peasantArray, the modified variable (var) is being modified/updated inside the object A after by printing out the variable status in a scheduled fashion; but if I am to loop through the NSMutableArray *peasantArray again in the next schedule (1/30s), I will again find the object A with the older/un-updated variable (var), and this is causing my algorithm to be wrong,
However, if I loop through the NSMutableArray *peasantArray less than 1second, each time I would see the variable (var) for object A correctly as the updated variable value,
So is there a limit on how fast I can iterate over the NSMutableArray?
here are some piece of code that I basically just mentioned,
NSMutableArray *peasantArray;
NSMutableArray *treeArray;
.....
peasantArray = [[[NSMutableArray alloc] initWithCapacity:1]retain];
for(int i = 0; i < 1; i++)
{
Peasant *A = [[Peasant alloc] init];
[peasantArray addObject:A];
}
....
//inside the update()
for (int i = 0;i < [peasantArray count];i++)
{
Peasant *A = [peasantArray objectAtIndex:i];
if (A.status == something)
{
printf("A.status is something\n");
A.status = sometingelse;
...
//update other things not related to this NSMutableArray or object
}
}
.....
SO the error is that sometimes I will have multiple printf of "A.status is something", although only one of it should be printed,
I really appreciate any help,
Thanks,
So is there a limit on how fast I can iterate over the NSMutableArray?
Definitely no. That would be the stupidest implementation of an array I'd ever encountered. :)
The simplest explanation is usually the answer. You say the message is printed more than once. Well have you checked that maybe more than one Peasant has its status set to something?
If that's not the case, are you certain the status update is printed twice in the same frame, and not twice in two subsequent updates?
Earlier on you seemed to indicate that the effect of iterating over one array and modifying the other array's objects is invalidated somehow. That made me want to point out that if you have the same object in both arrays, modifying the object's properties in array A will also modify the properties of the same object contained in array B.
You may want to give breakpoints a(nother) try. The problem should be easy to locate when you step through the code.
Here you have a memory leak
for(int i = 0; i < 1; i++)
{
Peasant *A = [[Peasant alloc] init];
[peasantArray addObject:A];
}
you should release A after adding it to the array since the addObject adds a reference count to the object.
for(int i = 0; i < 1; i++)
{
Peasant *A = [[Peasant alloc] init];
[peasantArray addObject:A];
[A release];
}
So, I'm struggling a bit with my programming project.
I have a object that stores player information, name, wins, losses.
I proceed to use that object in another object (a bracket) that sets the values of the player information, after each loop it copies the player object to a NSMutable in the bracket class.
Within the bracket class I have a method to print out the information, which was easy enough to figure out.
Now, to generate what will happen for the next bracket, I set up a method that will return a bracket when it's finished copying who won or lost.
I've done this all within the same bracket method so I could access the data as easily as possible. How do I simply just make a copy of the player object and add it to the new bracket?
I'm finding that I'm just getting garbage values or nothing at all when I try to print out the Bracket I've just generated. Here's my function that I'm having trouble with.
-(Bracket *) NextRound//Configures the next round
{
int i, y, *selection; //counter and selection
int comp;
y = 1;
i = 0;//so the counter won't get messed up
Bracket *roundx = [Bracket new]; //creates the bracket that will be sent back with the winners.
NSLog(#"Did %#(1) or %#(2) win (1 or 2)?: ",[[playerarray objectAtIndex:i] name], [[playerarray objectAtIndex:y] name]);
scanf("%d",&selection);
comp = selection++;
if (comp == 1)
{
NSLog(#"Player %d %# selected to win", i, [[playerarray objectAtIndex:i] name]);
[[self.playerarray objectAtIndex:i] setNext];//bool value for win or not
[roundx.playerarray addObject: [self.playerarray objectAtIndex:i]];
[roundx Print];//Too see if it has anything, usually it does not.
}
else
{
i++;
NSLog(#"Player %d %# selected to win", i, [[playerarray objectAtIndex:i] name]);
[[self.playerarray objectAtIndex:i] setNext];
[roundx.playerarray addObject: [self.playerarray objectAtIndex:i]];
[roundx Print];
}
return(roundx);
}
So, I thought that would just work. It compiles just fine (I get a few warnings, but it's about the integers and such that I use for logic mostly).
Thank You!
My comments:
The definition of selection is incorrect. You have defined it as a pointer to an int, but you are using it as if it were an int everywhere in your code. Note that selection++ increments selection by sizeof(int) not 1.
You shouldn't really be using -new to initialise objects but -alloc and then -init. (This is the modern convention).
The most likely cause of your problem is that playerarray is not initialised.