There are lots of examples on this site about adding to NSMutableArray and I have looked at many but I still don't either understand (highly possible) or am missing something fundamental.
I am trying to add to an NSMutableArray via a for loop. I want to keep track of button x,y coordinate position using the button tag as key/index so I can change a button as a user clicks it. This is all without IB.
My init is as follow:
self.tmpXpos = [[NSMutableArray alloc] init];
self.tmpYpos = [[NSMutableArray alloc] init];
[self.tmpXpos insertObject:[NSNull null] atIndex:0];
[self.tmpYpos insertObject:[NSNull null] atIndex:0];
**I added these after reading about 'creating' the array and populating it with null.
In the loop:
NSUInteger btag = button.tag; //NSUInterger as per help
>>NSNumber *xNumber = [NSNumber numberWithInteger:[self xpos]]; // NSNumber as an Object wrapper
>>NSNumber *yNumber = [NSNumber numberWithInteger:[self ypos]];
>>[self.tmpXpos insertObject:xNumber atIndex:btag];
>>[self.tmpYpos insertObject:yNumber atIndex:btag];
NSLog(#"%d, %#, %#",btag,xNumber,yNumber);
The log entries look ok:
2,64,0
3,128,0
etc for each button to be added to the screen.
During debugging - the tmpXpos and tmpYpos listed as " 0 Objects " under self.
I retrieve the information thusly:
NSUInteger tmpSt = [self.sTags integerValue];
NSNumber *tmpX = [self.tmpXpos objectAtIndex:tmpSt];
NSNumber *tmpY = [self.tmpYpos objectAtIndex:tmpSt];
int tmpPositionX = [tmpX intValue];
int tmpPositionY = [tmpY intValue];
NSLog(#"%d, %d",tmpPositionX, tmpPositionY);
NSLog yields 0, 0
I do appreciate any guidance or questions you folks might have as this site's 'sanity checks' have saved my bacon in the past.
I am ignoring memory leaks as of yet, but they are in the back of my mind. No worries there.
Ironically, I have a couple of other arrays that work just fine, but the exception is that they are not populated via a loop.
Lastly, the code works fine as the button at location 0,0 does change as per design, LOL, but not for any other location.
Thanks again!
Neil
I think your problem is that you are creating the NSNumbers with the method numberWithInteger, when an NSUInteger is actually an unsigned long. So try
xNumber = [NSNumber numberWithUnsignedLong:[self xpos]];
Trees for the forest answer. I wanted to populate an array with a quantity, however, the array expects that quantity to be in numerical sequence. My data didn't have any 'gaps' but wasn't in sequence either; I.E., 1,2,3,6,7,12 etc. So, as user397313 helped me see, NSDictionary is the way to go with that kind of datum.
Related
I get an array from a JSON and I parse it into an NSMutableArray (this part is correct and working). I now want to take that array and print the first object to a Label. Here is my code:
NSDictionary *title = [[dictionary objectForKey:#"title"] objectAtIndex:2];
arrayLabel = [title objectForKey:#"label"];
NSLog(#"arrayLabel = %#", arrayLabel); // Returns correct
//Here is where I need help
string = [arrayLabel objectAtIndex:1]; //I do not get the first label (App crashes)
NSLog(#"string = %#", string);
other things that I have already tried are as follows:
string = [NSString stringWithFormat:#"%#", [arrayImage objectAtIndex:1]];
and
string = [[NSString alloc] initWithFormat:#"%#", [arrayImage objectAtIndex:1]];
Any help is greatly appriciated!
EDIT: The app does not return a single value and crashes.
Your code doesn't match the structure of your JSON. In your comment on the deleted answer, you said you got an exception when sending objectAtIndex: to an NSString. In your case, arrayLabel isn't an array when you think it is.
If your JSON has an object, your code needs to treat it as an NSDictionary. Likewise for arrays and NSArray and strings and NSString.
In addition to whatever else was going on, you repeatedly refer to "first" but use the index 1. In most C-based programming languages (and others, as well) the convention is that indexes into arrays are 0-based. So, use index 0 to get the first element.
I am using this code in a loop to populate an NSMutable Array of NSMutableSets (of NSString objects). The index of the NSSet is based on the length of the word.
// if set of this length not initialized yet, initialize set.
wordIndex = [NSString stringWithFormat:#"%d", currentWordLength];
if ([myWordArray objectForKey:wordIndex] == nil)
[myWordArray setObject:[[NSMutableSet alloc] initWithObjects:currentWord, nil] forKey:wordIndex];
else
[[myWordArray objectForKey:wordIndex] addObject:currentWord];
The final intention is to split up an array of words into an array of sets of words grouped by their lengths.
However, I see that [myWordArray count] is 0 after this. Why?
You are confusing the methods of NSMutableDictionary and NSMutableArray: In Objective-C arrays do not have keys but have indexes. If you change the class for myWordArray to NSMutableDicitionary it should work.
Try this, it looks very much like your logic, but (1) it uses NSNumbers as keys, which makes a little more sense, (2) handles the missing set condition more simply, but just adding the set, and (3) breaks up the source lines somewhat for easier debugging...
NSArray *inputStrings = // however these are initialized goes here
NSMutableDictionary *result = [NSMutableDictionary dictionary];
for (NSString *currentString in inputStrings) {
NSInteger currentWordLength = currentString.length;
wordIndex = [NSNumber numberWithInt:currentWordLength];
NSMutableSet *wordSet = [result objectForKey:wordIndex];
if (!wordSet) {
wordSet = [NSMutableSet set];
[result setObject:wordSet forKey:wordIndex];
}
[wordSet addObject:currentWord];
}
If you still have an empty dictionary after running this, it might be simpler to watch what's happening by stepping through it.
I'm still very much a noob, having a lot of fun learning the basics of Objective-C, using XCode to put together some simple programs for OS-X.
I have a program which ranks a five card poker hand.
Each card in the deck is identified by its unique 'index number' (0-51)
To speed up the evaluator I thought it would be useful to have an array containing all possible combinations of five indices (there are 2598960 of these).
If I do this:
NSMutableArray *allPossibleHands = [[NSMutableArray alloc] initWithObjects: nil];
for(int i = 0; i<48; i++)
{
for(int j = i+1; j<49; j++)
{
for(int k = j+1; k<50; k++)
{
for(int m = k+1; m<51; m++)
{
for(int n = m+1; n<52; n++)
{
NSNumber *number0 = [NSNumber numberWithInt: i];
NSNumber *number1 = [NSNumber numberWithInt: j];
NSNumber *number2 = [NSNumber numberWithInt: k];
NSNumber *number3 = [NSNumber numberWithInt: m];
NSNumber *number4 = [NSNumber numberWithInt: n];
NSArray *nextCombination = [[NSArray alloc] initWithObjects: number0,number1,number2,number3,number4,nil];
[allPossibleHands addObject: nextCombination];
}
}
}
}
}
NSLog(#"finished building allPossibleHands. It contains %i objects", [allPossibleHands count]
);
everything seems to work fine, and I get a message to say that my array contains, as expected, 2598960 objects. I can then list all the elements of my array.
But I thought wrapping my ints in NSNumber objects like that must take up a lot more memory. Maybe storing the index numbers as short ints would be better.
However, if, instead of building my array as above, I do this:
`short int allPossibleHands[2598960][5]`;
intending to then use my loop to store the ints directly, I get a EXC_BAD_ACCESS error message and a note that there's no memory available to the program.
So how come I can store all those NSNumber objects, but not the ints?
Is there some rule about array construction that I'm breaking?
As always, any guidance much appreciated.
Thank You for reading this.
While the second is allocated on the stack (which is much more limited in size), the first one is allocated on the heap and is a pointer to a memory area.
This does not mean that the first one takes less space. If you allocated the second array as a pointer, the error would go away.
Also read the answers to this question.
Assuming that an NSNumber object must store the value and the type of the number, it is probably a little larger than an int.
But if your int[][] array is a local variable, it is very likely stored on the stack, and most stacks are not that large. You could use a pointer to such an array and malloc it on the heap, which probably has enough room for it.
Accessing a C array is very likely a little faster than accessing that many NSNumbers in an NSArray and extracting their values, and if this is for a card game, speed is probably an issue.
I think the problem is where you are storing your array. Is it on the stack? If so, keep in mind it's going to be 25MB so much larger than most stacks allow.
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.
a big noob needs help understanding things.
I have three UIViews stored inside a NSMutableArray
lanes = [[NSMutableArray arrayWithCapacity:3] retain];
- (void)registerLane:(Lane*)lane {
NSLog (#"registering lane:%i",lane);
[lanes addObject:lane];
}
in the NSLog I see: registering lane:89183264
The value displayed in the NSLog (89183264) is what I am after.
I'd like to be able to save that number in a variable to be able to reuse it elsewhere in the code.
The closest I could come up with was this:
NSString *lane0 = [lanes objectAtIndex:0];
NSString *description0 = [lane0 description];
NSLog (#"description0:%#",description0);
The problem is that description0 gets the whole UIView object, not just the single number (dec 89183264 is hex 0x550d420)
description0's content:
description0:<Lane: 0x550d420; frame = (127 0; 66 460); alpha = 0.5; opaque = NO; autoresize = RM+BM; tag = 2; layer = <CALayer: 0x550d350>>
what I don't get is why I get the correct decimal value with with NSLog so easily, but seem to be unable to get it out of the NSMutableArray any other way. I am sure I am missing some "basic knowledge" here, and I would appreciate if someone could take the time and explain what's going on here so I can finally move on. it's been a long day studying.
why can't I save the 89183264 number easily with something like:
NSInteger * mylane = lane.id;
or
NSInteger * mylane = lane;
thank you all
I'm really confused as to why you want to save the memory location of the view? Because that's what your '89183264' number is. It's the location of the pointer. When you are calling:
NSLog (#"registering lane:%i",lane);
...do you get what's actually being printed out there? What the number that's being printed means?
It seems like a really bad idea, especially when if you're subclassing UIView you've already got a lovely .tag property which you can assign an int of your choosing.
You're making life infinitely more complex than it needs to be. Just use a pointer. Say I have an array containing lots of UIViews:
UIView *viewToCompare = [myArray objectAtIndex:3];
for (id object in myArray) {
if (object == viewToCompare) {
NSLog(#"Found it!");
}
}
That does what you're trying to do - it compares two pointers - and doesn't need any faffing around with ints, etc.