for(int i=0;i<[promotionArr count];i++)
{
// NSLog(#"ok");
Promotion *prom = [[Promotion alloc]init];
prom.pName=[[promotionArr objectAtIndex:i] objectForKey:#"name"];
prom.pUrl=[[promotionArr objectAtIndex:i] objectForKey:#"url"];
prom.pDescription=[[promotionArr objectAtIndex:i] objectForKey:#"description"];
[promMUAraay addObject:prom];
NSLog(#"number of elements : %d",[promMUAraay count]);
}
But the number of element is always 0 . I haven't do #synthetise for the NSMutableArray , xcode tell me that i can't .I just do this in my .h
NSMutableArray *promMUAraay;
It's that the problem ?
Have you remembered to alloc, init the array?
NSMutableArray *array = [[NSMutableArray alloc] init];
Do this before you use the array.
You should initialize your NSArray before accessing it. That is, in your .m file, in your -init method, you should have some code like this:
promMUAraay = [[NSMutableArray alloc] init.......];
For all the options you have initializing an NSArray, see the NSArray reference.
As to your attempt at syntethizing the array, the #synthetize keyword is used to automatically create definitions for setter/getter methods to your array (provided you have a corresponding #property declaration in your interface). This does not change things in that you would all the same need to initialize your NSArray in the init method of your class. The only thing is that you could thereafter refer your variable using the dot-notation: self.promMUAraay.
Related
I'm using this code with ARC:
NSMutableDictionary *datesDict = [[NSMutableDictionary alloc]init];
NSMutableArray *datesArray = [[NSMutableArray alloc]init];
for (NSString *key in programsArray) {
datesArray = [_onDemandDictionary objectForKey:key];
NSMutableArray *newDates = [[NSMutableArray alloc]init];
int count;
for (count = 0; count <datesArray.count; count++) {
NSMutableDictionary *programsDict = [[NSMutableDictionary alloc]init];
programsDict = [datesArray objectAtIndex:count];
[newDates addObject:[programsDict objectForKey:#"date"]];
}
[datesDict setObject:newDates forKey:key];
}
But when I run the analyzer tool I'm getting value stored to (datesArray and programsDict) during its initialization is never read on lines:
NSMutableArray *datesArray = [[NSMutableArray alloc]init];
programsDict = [datesArray objectAtIndex:count];
Why is this happening how do I get hid of the warning?
Thank you!
The issue is you create a new NSMutableArray and assign it to datesArray at the beginning
NSMutableArray *datesArray = [[NSMutableArray alloc]init];
Then almost immediately after you assign a completely different value to datesArray with
datesArray = [_onDemandDictionary objectForKey:key];
I would just start with
NSMutableArray *datesArray = nil;
It's the same concept for programsDict.
On line 2, you create a new array datesArray.
Then, on line 6 (first line of the for loop), you set a new value to datesArray.
The compiler is just warning you that the line 2 has no effect, and that the code is bugged (in the sense it does not do what you expect).
True, the programsArray could be an empty array, and in this case you want datesArray to just be initialized to use it after the snippet you showed us, but it would be better to make this explicit.
For programsDict, it is even easier: you initialize it with ... alloc] init] then set it to an object of datesArray, making the first operation useless.
You are not using datesArray in your loop, you are simply assigning it values, So either take it nil array like
NSMutableArray* datesArray = nil;
or like
NSMutableArray *datesArray;
to remove waring .
Ok so I populate the array like this:
NSMutableArray *participants;
for(int i = 0; i < sizeofpm; i++){
NSDictionary *pmpart_dict = [pm_participants objectAtIndex:i];
NSString *pmpart_email = [pmpart_dict objectForKey:#"email"];
NSString *pmpart_email_extra = [#"pm" stringByAppendingString:pmpart_email];
[participants setValue:pmpart_email forKey:pmpart_email_extra];
NSLog(#"%#", participants);
}
sizeofpm is 1. that is using count. to get the number of values in the array. How can i store values to that array? It doesnt seem to be working. Thanks!
you need to alloc it first. Try to change the first line to:
NSMutableArray* participants = [[NSMutableArray alloc] init];
also using setValue:forKey: wont work with an NSMutableArray as an array has no key.
Try using [participants addObject:pmpart_email];.
You don't create the array, you just declare it.
NSMutableArray *participants = [NSMutableArray array];
After that, setValue:forKey: will not add objects to an array. You need addObject::
[participants addObject:pmpart_email];
There is no key.
You are assigning a value to an NSMutableArray *participants like how you assign values to an NSDictionary object. To assign values to NSMutableArray you can call - (void)addObject:(id)anObject
So, I as some of the other answer have stated, you're missing your initializer for participants. However, judging by your use of setValue:forKey:, and how you appear to be structuring your data, you're not looking for NSMutableArray, but instead NSMutableDictionary. Arrays are simply lists, whereas dictionaries maintain key-value relationships, which you appear to be attempting to leverage.
Try this:
// some classes provide shorthand for `alloc/init`, such as `dictionary`
NSMutableDictionary *participants = [NSMutableDictionary dictionary];
for(int i = 0; i < sizeofpm; i++){
NSDictionary *pmpart_dict = [pm_participants objectAtIndex:i];
NSString *pmpart_email = [pmpart_dict objectForKey:#"email"];
NSString *pmpart_email_extra = [#"pm" stringByAppendingString:pmpart_email];
[participants setValue:pmpart_email forKey:pmpart_email_extra];
NSLog(#"%#", participants);
}
This will give you a dictionary in the form of
{
pmpart_email_extra: pmpart_email
}
I am trying to create a mutable array with objects of a custom class called Dog and save it to a file in the iPhone documents directory to be later read out of the file and back into my application. I am trying to use NSArray's writeToFile:atomically: method to accomplish this, but when I test the results of this method, it always returns a value of NO, and the file is not created, and the array is not stored. I have a few questions about this. What file format should I save my array to? What does it mean to atomically write an array to a file? How do I read out the contents of the file once the array is stored there And most importantly, why is my array not being stored into a file at the specified path? Thank you in advance and here is the code that I am using within my app's viewDidLoad method:
NSString *documentsDir = [NSSearchPathForDirectoriesInDomains
(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex: 0];
dogFilePath = [documentsDir stringByAppendingPathComponent:#"arrayDogsFile.plist"];
NSFileManager *fileManager = [[NSFileManager alloc] init];
NSLog(#"%#",dogFilePath);
Dog *dog1 = [[Dog alloc] init];
dog1.name = #"Dog1";
Dog *dog2 = [[Dog alloc] init];
dog2.name = #"Dog2";
Dog *dog3 = [[Dog alloc] init];
dog3.name = #"Dog3";
NSMutableArray *arrayDogs = [NSMutableArray array];
[arrayDogs addObject: dog1];
[arrayDogs addObject: dog2];
[arrayDogs addObject: dog3];
//Sorts the array in alphabetical order according to name – compareDogNames: is defined in the Dog class
arrayDogs = (NSMutableArray *)[arrayDogs sortedArrayUsingSelector:#selector(compareDogNames:)];
if ([arrayDogs writeToFile:dogFilePath atomically:YES])
NSLog(#"Data writing successful");
else
NSLog(#"Data writing unsuccessful");
You can not save your array of objects because objects are not NSString, NSData, NSArray, or NSDictionary.You could rather use NSKeyArchiver and NSKeyUnArchiver
For example:
#import "Foundation/Foundation.h"
#interface Dog : NSObject {**NSCoding**}//your class must conform to NSCoding Protocol
#property (retain) NSString *Name;
#end
The implementation needs some additional code. We need to implement the NSCoding protocol, which means
two additional methods. (initWithCoder: and encodeWithCoder:)
#import "Dog.h"
#implementation Dog
#synthesize Name;
-(id)initWithCoder:(NSCoder*)decoder{
if ((self = [super init])) {
Name = [decoder decodeObjectForKey:#"Name"];
}
return self;
}
-(void)encodeWithCoder:(NSCoder*)encoder{
[encoder encodeObject:Name forKey:#"Name"];
}
Once we implement the protocol, saving will look like this:
// Save method
// We initialise our object and set the values
Dog *dog1 = [[Dog alloc] init];
dog1.Name= #"Dog1";
Dog *dog2 = [[Dog alloc] init];
dog2.Name= #"Dog2";
Dog *dog3 = [[Dog alloc] init];
dog3.Name= #"Dog3";
NSMutableArray *arrayDogs = [NSMutableArray array];
[arrayDogs addObject: dog1];
[arrayDogs addObject: dog2];
[arrayDogs addObject: dog3];
//Sorts the array in alphabetical order according to name – compareDogNames: is defined in the Dog class
arrayDogs = (NSMutableArray *)[arrayDogs sortedArrayUsingSelector:#selector(compareDogNames:)];
// Store the array
[NSKeyedArchiver archiveRootObject:arrayDogs toFile:dogFilePath];
//load the array*
NSMutableArray* retreivedADogObjs = [NSKeyedUnarchiver unarchiveObjectWithFile:dogFilePath];
#end
Hope it will help you
Happy to help.*
Look at NSKeyedArchiver & NSKeyedUnarchiver Specifically you want + archiveRootObject:toFile: to save the file and + unarchiveObjectWithFile: to extract it again.
You will need to implement the NSCoding protocol in your Dog class as well to make this work. You just need to use something like - encodeObject: forKey: and – decodeObjectForKey: for each of your properties. The docs for NSCoder will show you which method to use for which kinds of property types (for example with BOOLs you use - encodeBool: forKey:).
Industrial answer:
There's a whole subject for this in the SDK called "Archiving and Serialization".
If you don't have time to learn, but your dog does:
Teach your Dog two new tricks: 1. How to render myself as a dictionary of strings and ints and so on. 2. How to init myself from that same kind of dictionary. This is basically a ghetto version of the industrial answer.
// Dog.m
- (NSDictionary *)asDictionary {
NSMutableDictionary *answer = [NSMutableDictionary dictionary];
[answer setValue:self.name forKey:#"name"];
[answer setValue:self.numberOfBones forKey:#"numberOfBones"];
return [NSDictionary dictionaryWithDictionary:answer];
}
- (id)initWithDictionary:(NSDictionary *)dictionary {
self = [super init];
if (self) {
self.name = [dictionary valueForKey:#"name"];
self.numberOfBones = [dictionary valueForKey:#"numberOfBones"];
}
return self;
}
When writing:
[arrayDogs addObject: [dog1 asDictionary]];
I want to know that how can I add NSMutableArray in to an NSMutableArray so that previous data should not lost, and new data will be added on next indexes.
If you don't understand it then you can ask again to me,
I will appraise the right answer.
my code is as below
-(void)setArray1:(NSMutableArray *)arrayValueFromNew
{
self.myArray=arrayValueFromNew;
myArray2 = [[NSMutableArray alloc] initWithArray:arrayValueFromNew];
for(int i=0;i<[myArray2 count];i++)
{
[myArray addObject:[myArray2 objectAtIndex:i]];
}
}
In your code, myArray and myArray2, both have same objects as you are assigning the arrayValueFromNew array to both. So it kind of doesn't make sense.
But to answer your question 'how to add one array to another?' do :
[mutableArray1
addObjectsFromArray:array2];
EDIT:
this is how your method should look
-(void)setArray1:(NSMutableArray *)arrayValueFromNew
{
if(!self.myArray)
{
self.myArray = arrayValueFromNew;
}
else
{
[self.myArray addObjectsFromArray:arrayValueFromNew];
}
}
Your 'myArray must be initialized. You can initialize it in viewDidLoad or init:
self.myArray = [[NSMutableArray alloc]
initWithCapacity:1];
NSMutableArray *array1 = [NSMutableArray array], *array2 = [NSMutableArray array];
// add some objects to the arrays
[array1 addObjectsFromArray:array2];
//array1 now contains all the objects originally in array1 and array2
This will work,
NSMutableArray *mutarr=[[NSMutableArray alloc]initWithArray: array1]
It looks like you just want a new copy of the old array. There is a handy function for that
NSMutableArray *newArray = [oldArray mutableCopy];
Remember that you've used copy in getting this array so you are responsible for managing the memory of newArray
EDIT
What is your code doing?
-(void)setArray1:(NSMutableArray *)arrayValueFromNew //1
{
self.myArray=arrayValueFromNew; //2
myArray2 = [[NSMutableArray alloc] initWithArray:arrayValueFromNew]; //3
for(int i=0;i<[myArray2 count];i++)
{
[myArray addObject:[myArray2 objectAtIndex:i]]; //4
}
}
This looks like a setter for a property array1
You are setting the property 'array' to arrayValueFromNew. Since I don't know whether this property has been declared with retain or copy I don't know whether array is a pointer to arrayValueFromNew or a pointer to a copy of arrayValueFromNew
You set myArray2 to be a new array that contains the objects of arrayValueFromNew
For each object in myArray2 (which are the objects from arrayValueFromNew. see point 3) you add this object to myArray. Assuming myArray is an NSMutableArray it started with the objects from arrayValueFromNew which you have now added again. It contains each item in arrayValueFromNew twice.
Just a conceptual description first:
I am reading input from a text file (a list of words) and putting these words into an NSArray using componentsSeparatedByString method. This works.
But I wanted to select the words randomly and then delete them from the array so as to ensure a different word each time. Of course, you cannot change the NSArray contents. So...
I copied the contents of the NSArray into an NSMutableArray and use IT for the selection source. This also works - 269 objects in each array.
To return a word from the NSMutableArray I use the following code:
note- the arrays are declared globally
as
arrMutTextWords = [[NSMutableArray alloc] init]; //stack for words
arrTextWords = [[NSArray alloc] init]; //permanent store for words
-(NSString*) getaTextWord
{
// if the mutable text word array is empty refill
if ([arrMutTextWords count] == 0){
for (int i = 0 ; i < [arrTextWords count]; i++)
[arrMutTextWords addObject:[arrTextWords objectAtIndex:i]];
}
int i = random() % [arrMutTextWords count];
NSString* ptrWord = [arrMutTextWords objectAtIndex:i];
[arrMutTextWords removeObjectAtIndex:i];
return ptrWord;
}
The program crashes during a call to the method above - here is the calling code:
arrTmp is declared globally arrTmp = [[NSArray alloc] init]; //tmp store for words
for (int i = 0 ; i < 4; i++) {
tmpWord = [self getaTextWord];
[arrTmp addObject:tmpWord];
[arrTmp addObject:tmpWord];
}
I'm thinking that somehow deleting strings from arrMutTextWords is invalidating the NSArray - but I can't think how this would occur.
One possible source for problems is your fetching AND removing the NSString object from your list. Removing it releases that NSString instance therefore devalidating your reference.
To be shure to retain a reference you should use this code sequence instead:
NSString * ptrWord = [[[arrMutTextWords objectAtIndex:i] retain] autorelease];
[arrMutTextWords removeObjectAtIndex:i];
return ptrWord;
By the way: You should use
NSMutableArray *mutableArray = [NSMutableArray arrayWithArray: array];
instead of copying all values by hand. While i do not know the implementation of NSMutableArray, i know from times long ago (NeXTstep), that there are several possible optimizations that may speed up basic NSArray operations.
And finally copying this way is much more concise.
Just ran this through XCode and got random words returned, however I skipped the whole for loop and used addObjectsFromArrayfrom NSMutableArray.
NSArray *randomArray = [[NSArray alloc] initWithObjects:#"Paul", #"George", #"John", nil];
NSMutableArray *muteArray = [[NSMutableArray alloc] init];
[muteArray addObjectsFromArray:randomArray];
int i = random() % [muteArray count];
NSString* ptrWord = [muteArray objectAtIndex:i];
[muteArray removeObjectAtIndex:i];
NSLog(#"ptrWord %#", ptrWord); //gave me a different name each time I ran the function.
Hope this clears some things up.