How wouold i do this with a nsmutablearray, its simple with a nsarray just not a mutable array
Thanks
Just create mutable array from non-mutable that you get from that message:
NSMutableArray *mutableComponents = [NSMutableArray arrayWithArray:[yourString componentsSeparatedByString:...]];
The following will work too:
NSMutableArray *mArray = (NSMutableArray *)[yourString
componentsSeparatedByString:#"separator"];
You might need to retain and release when you're done.
Use the following code.
NSArray *array = [someString componentsSeparatedByString:#" "];
NSMutableArray *mutArray = [[NSMutableArray alloc] initWithArray:array];
use the mutArray, this is one NSMutableArray object.
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 have an NSMutableArray which has five objects in it. I want to insert an object in the middle of an array, let me say atIndex 1, and move all the objects to index+1 how do I do that?
Can you please help me?
Use insertObject
NSMutableArray *arr = [[NSMutableArray alloc] init];
[arr insertObject:#"OBJ" atIndex:1];
With insertObject:AtIndex: method of NSMutableArray.
See docs.
NSMutableArray *arr = [[NSMutableArray alloc] initWithObjects:#"1",#"2",#"3",#"4",nil];
[arr insertObject:#"2" atIndex:[arr count]/2];
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 would simply like to know how to copy a NSMutableArray so that when I change the array, my reference to it doesn't change. How can I copy an array?
There are multiple ways to do so:
NSArray *newArray = [NSMutableArray arrayWithArray:oldArray];
NSArray *newArray = [[[NSMutableArray alloc] initWithArray:oldArray] autorelease];
NSArray *newArray = [[oldArray mutableCopy] autorelease];
These will all create shallow copies, though.
(Edit: If you're working with ARC, just delete the calls to autorelease.)
For deep copies use this instead:
NSMutableArray *newArray = [[[NSMutableArray alloc] initWithArray:oldArray copyItems:YES] autorelease];
Worth noting: For obvious reasons the latter will require all your array's element objects to implement NSCopying.
I want to split string into NSMutableArray
I know
- (NSArray *)componentsSeparatedByString:(NSString *)separator
is available but this one is for NSArray not for NSMutableArray.
I need because after spliting i want to remove element from array by using
-(void)removeObjectAtIndex:(NSUInteger)index
which is not possible with NSArray.
Thank you
You can also just get a mutable copy of the returned array:
NSMutableArray *array = [[myString componentsSeparatedByString:#"..."] mutableCopy];
Also, remember that copy, like alloc, does allocate new memory. So when used in non-ARC code you must autorelease the copied array or manually release it when you are done with it.
Make a new NSMutableArray using
NSArray *array = [NSString componentsSeparatedByString:#"..."];
NSMutableArray *mutable = [NSMutableArray arrayWithArray:array];
Create a NSMutableArray from the output NSArray created by componentsSeparatedByString.
NSMutableArray *mutableArray = [[NSMutableArray alloc] initWithArray:array];