I am making an iphone app in which I want to store the dynamically selected time into an array, but unable to implement the method to store the strings into an array. Following is the code which I am using but it is not giving the output.
- (void)storetimeintoanarray:(id)sender
{
NSDateFormatter *df3 = [[NSDateFormatter alloc] init];
[df3 setDateFormat:#"hh:mm:ss"];
timestr = [NSString stringWithFormat:#"%#",[df3 stringFromDate:objtimepicker.date]];
NSLog(#"time is:%#",timestr);
test = [[NSArray alloc]init];
[test arrayByAddingObject:timestr];
NSLog(#"array time:%#",test);
}
You have to declare array mutable object.
test = [[NSMutableArray alloc]init];
[test addObject:timestr];
You have to assign the result of the arrayByAddingObject: method to a new array like:
NSArray *newone = [test arrayByAddingObject:timestr];
After allocating you shouldn't allocate the array again. arrayByAddingObject returns a auto released new array. Also use a NSMutableArray when you want to add objects dynamically.
Change the code to
test = [[NSMutableArray alloc]init];
[test addObject:timestr];
You should be using NSMutableArray if you want to change it after creation.
NSMutableArray* arr = [[NSMutableArray alloc] init];
[arr addObject:timestr];
To create an array with a single object, you can use:
NSArray* arr = [NSArray arrayWithObject:timestr];
You should use NSMutableArray and its method addObject: instead of NSArray. [test arrayByAddingObject:timestr]; does nothing with your array test, its create new array
Related
I´m doing an app and I can´t get a mutable array to accept objects. I´v tried setting breakpoints to see what´s happening but it keeps saying that the mutable array is nil. Does anyone has an answer?
My code:
- (void)save:(id) sender {
// All the values about the product
NSString *product = self.productTextField.text;
NSString *partNumber = self.partNumberTextField.text;
NSString *price = self.priceTextField.text;
NSString *quantity = self.quantityTextField.text;
NSString *weigh = self.weighTextField.text;
NSString *file = [self filePath];
//Singleton class object
Object *newObject = [[Object alloc] init];
newObject.product = product;
newObject.partNumber = partNumber;
newObject.price = price;
newObject.quantity = quantity;
newObject.weigh = weigh;
//Array declaration
mutableArray = [[NSMutableArray alloc]initWithContentsOfFile: file];
[mutableArray addObject:newObject];
[mutableArray writeToFile:file atomically:YES];
}
While initWithContentsOfFile: can be called on an NSMutableArray, it was inherited from NSArray. The return value is an NSArray which is not mutable. If you want to add objects to your mutable array, you have to do something like this:
mutableArray = [[[NSMutableArray alloc] initWithContentsOfFile: file] mutableCopy];
[mutableArray addObject:newObject];
[mutableArray writeToFile:file atomically:YES];
Now, the addObject: call should work.
Best regards.
[NSMutableArray initWithContentsOfFile:] returns nil by default if the file can't be opened or parsed. Are you sure the file you're loading exists and is formatted correctly?
Try to check with break point on
mutableArray = [[NSMutableArray alloc]initWithContentsOfFile: file];
Line. Move your cursor on mutableArray if it shows you __NSArrayI that means it is an immutable array i.e. you cant update it and if it shows you __NSArrayM that means it is a mutable array and you can update this array.
In your case you're getting immutable array thats why you cant update it.
So you have two way to get mutable Array from this file -
Method:1
mutableArray = [[[NSMutableArray alloc] initWithContentsOfFile: file] mutableCopy];
Method:2
NSArray *anyArray = [[NSArray alloc]initWithContentsOfFile: file];
mutableArray = [[NSMutableArray alloc]initWithArray:anyArray];
In both case mutableArray woud be a mutable Array. You can update it.
I'm try to use the functions -setValue:forKey: and get the value using -valueForKey:
Example:
NSArray *rootarr = [[NSArray alloc] init];
NSArray *array = [[NSArray alloc] initWithObjects:#"name", #"address", #"title", nil];
[rootarr setValue:array forKey:#"n"];
NSArray *getArr = [rootarr valueForKey:#"n"];
But the getArr array I got is not equal the array I set (array).
Could you please tell me what's wrong I met. And what's the way to use these functions?
NSArray's setValue:forKey: method is used for Key Value Coding, not for using an array as an associative container. You need to use NSMutableDictionary.
NSMutableDictionary *rootDict = [NSMutableDictionary dictionary];
NSArray *array = [[NSArray alloc] initWithObjects:#"name", #"address", #"title", nil];
[rootDict setValue:array forKey:#"n"];
NSArray *getArr = [rootDict valueForKey:#"n"];
An array isn't a key-value store, which you appear to want to use it as. I think you want an NSDictionary instead (or more precisely NSMutableDictionary if you want to modify it after its created).
According to the Apple documentation setValue:forKey:
Invokes setValue:forKey: on each of the array's items using the specified value and key.
Practical uses are when you want to set the same value to each element of the array
UILabel *label1 = [[UILabel alloc]init];
UILabel *label2 = [[UILabel alloc]init];
NSArray *arr = #[label1, label2];
[arr setValue:#"bye" forKey:#"text"];
NSLog(#"%# %#",label1.text, label2.text); // bye bye
in your example "getArr" is an empty array because your "rootarr" doesn't have elements, otherwise you receive a setValue:forUndefinedKey: into the contained objects that are not compliant for the assigned key
You can't add objects to an NSArray after it is created. You have to use NSMutableArray in order to do that.
I have an NSMutableArray filled with Task objects. I want to be able to delete those whose completed property are set to YES
NSMutableArray *allTasks = (NSMutableArray *)[[TaskStore defaultStore] allTasks];
NSMutableArray *completedTasks;
for (Task *task in allTasks) {
if ([task completed]) {
[completedTasks addObject:task];
}
}
[allTasks removeObjectsInArray:completedTasks];
While debugging I noticed that the completedTasks array is always empty. Why is this?
You forgot to initialize the completedTasks :
NSMutableArray *completedTasks = [NSMutableArray array];
You haven't initialized completedTasks. You need to add this:
NSMutableArray *completedTasks = [[NSMutableArray alloc] init];
You must initialize the array before you can use it, the initializing actually creates your array object -
To do this add This Line to create an autoreleased array (which means you dont have to release it)
NSMutableArray *completedTasks = [NSMutableArray array];
Or
NSMutableArray *completedTasks = [[NSMutableArray alloc] init];
But then you will have to release it by yourself [completedTasks release] when you are not using it any moere (unless you are using ARC).
This will create your array object.
Shani
from NSMutableArray documentation :
This method assumes that all elements in otherArray respond to hash and isEqual:.
You can try :
[allTasks filterUsingPredicate:[NSPredicate predicateWithFormat:#"completed = %#", [NSNumber numberWithBool:YES]]]
I have an array called addArray which I am adding array objects to:
NSMutableArray *addArray = [NSMutableArray array];
[addArray addObjectsFromArray: delegate.arrayobjectOne];
[addArray addObjectsFromArray: delegate.arrayobjectTwo];
// etc...
Now, if I only want to init one of these arrays to display in my table (preferably from another view controller but that's another question), how would I do this? And how would I access a specific property of each array object, e.g. arrayobjectOne.info?
Thanks for your time.
you can say
someObject = [addArray objectAtIndex: someIndex];
use this Example
NSMutableArray *objectsToAdd= [[NSMutableArray alloc] initWithObjects:#"one",#"two", nil];
NSMutableArray *myArray = [[NSMutableArray alloc] initWithObjects:objectsToAdd,nil];
self.list = [[NSMutableArray alloc] init];
[self.list addObjectsFromArray:myArray];
I am trying to get the following loop working to fill an array of arrays:
while (condition) {
[itemsArray fillFromDB];
if (! [checkArray containsObject:checkFlag]) {
// Add existing itemsArray to myArray
if (itemsArray.count) {
// add the itemsArray to myArray and create a new instance of itemsArray
[myArray addObject:itemsArray];
[itemsArray release];
NSMutableArray *itemsArray = [[NSMutableArray alloc] init];
}
[itemsArray addObject:myObject];
[checkArray addObject:checkFlag];
} else {
[itemsArray addObject:tmpEvent];
} }
However I try to shape this loop it falls over the release of itemsArray
when I use release (as above), the array does not re-initialise as a new instance with alloc. Whilst expecting emptyness, the next Object is added to the old array.
when I use removeAllObjects, my Array is emptied and so is the array attached to myArray.
Where am I going in the wrong direction?
You might place:
itemsArray = nil;
after the release message, to ensure that you're not pointing to an old instance.
EDIT
Looking at this again, you have:
NSMutableArray *itemsArray = [[NSMutableArray alloc] init];
This is scoped within the if statement.
So take out NSMutableArray and just use:
itemsArray = [[NSMutableArray alloc] init];
Don't write NSMutableArray *itemsArray = [[NSMutableArray alloc] init];--you're re-declaring the variable in the scope of the if statement, so outside the if statement, itemsArray will still refer to the old value (I'm not sure why the compiler isn't complaining). You can just say itemsArray = [[NSMutableArray alloc] init] instead.
You also might want to use autorelease, to simplify, as well.
The others have found the problem, but have created a new problem. The first time you create the mutable array, you need to use NSMutableArray *itemsArray = [[NSMutableArray alloc] init];. Then, after, you can release and use itemsArray = [[NSMutableArray alloc] init];. It is important that the first one (the one that creates the pointer) occurs only once, and the rest can occur as many times as desired.
EDIT:
You could write NSMutableArray *itemsArray; before the if statement, and then use itemsArray = [[NSMutableArray alloc] init]; in the if statement.