Helo! How can i convert a NSMutableArray object to a NSString ? i try to do something like
cell.textLabel.text = [cars objectAtIndex:indexPath.row];
But it doesn't work, my app crashes. If i do something like
cell.textLabel.text =#"yes";
The app loads very nicely(but instead of the elements from the "cars" NSMutableArray i have a view table filled with "yes") . Any idea what the problem is ?
Is the NSMutableArray alloc'd and init'd properly? If you don't call cars = [[NSMutableArray alloc] init] before you use it, the array will not respond to adding objects to it. Make sure that's not the case. Also make sure that the elements in the cars array are NSStrings.
Make sure your cards contains enough cars, if the indexPath.row is large than the cards's count-1, it will crash.
Related
I'v run into such problem. I need to update the values in my NSArray. And don't know a way to do it. Here's my array
NSArray *arrayWithInfo = [[NSArray alloc] initWithObjects:AMLocalizedString(#"Status", nil),AMLocalizedString(#"Call", nil),AMLocalizedString(#"Location", nil),AMLocalizedString(#"Control", nil),AMLocalizedString(#"Sim", nil),AMLocalizedString(#"Object", nil),AMLocalizedString(#"Info", nil),nil];
self.dataArray = arrayWithInfo;
[arrayWithInfo release];
To be more specific I have tableview initialized with this array. There is a possibility for user to use different localized strings, so I have to update it. By using [tableview reloadData]; i'v got the table to update, but the values in NSArray stay the same as they were initialized in first place.
So how to make array look up at the strings once again and get their new values?
Use NSMutableArray instead of NSArray
NSMutableArray (and all other classes with Mutable in the name) can be modified.
You should be using an NSMutableArray. Doing so will allow you to change its values after instantiation.
Your array doesn't need to be mutable here as the array seems to be all or nothing. You dont mention the requirement to delete some objects and not others. NSMutableArray isn't needed. You want to write a lazy loading getter method for the array which reinstantiates it if the array doesnt exist.
-(NSArray *)dataArray{
if (_dataArray){
return _dataArray;
}
_dataArray = NSArray *arrayWithInfo = [[NSArray alloc] initWithObjects:AMLocalizedString(#"Status", nil),AMLocalizedString(#"Call", nil),AMLocalizedString(#"Location", nil),AMLocalizedString(#"Control", nil),AMLocalizedString(#"Sim", nil),AMLocalizedString(#"Object", nil),AMLocalizedString(#"Info", nil),nil];
return _dataArray;
}
Then when you want to reload the tableView
self.dataArray = nil;
[tableView reloadData];
this destroys the old array, forcing it to be remade but with the new localisation.
EDIT:
The issue is the array isn't storing the statement AMLocalizedString(#"Status", nil) its storing the result of that statement, which is the localised string itself. There is no way to make the array re-evaluate that statement without either re-creating the whole array again or using an NSMutableArray and changing all the objects. The lazy loading getter method is more in the objective-c style.
You need to use the NSMutableArray. The NSArray is immutable.
I trying to add a data on table view via Array Controller thats bind to a NSMutableArray.
On the IB property it looks like this :
and on the code I tried to add the NSMutableArray dynamically then reload the view, bu nothings happened.
for(int i=0;i<10;i++){
NSMutableDictionary *group = [[NSMutableDictionary alloc]init];
[group setValue:[NSString stringWithFormat:#"%#-%d", #"Group", i] forKey:#"groupname"];
[contentArray addObject:group];
}
[tableContent reloadData];
I have been google it and browse the same question in stackoverflow, not found a useful one.
any idea ?
Thanks
updated
I wrote above code in File's owner class.
I think the problem is that the array needs to send a KVO notification to the array controller (or maybe it's the table view, I'm not sure). The way to do that is:
self.contentArray = contentArray; (or _contentArray if that's what your ivar is called). I'm assuming that contentArray is a property, if not, you should make it one.
I am trying to save an image in an NSMutable array and it is not working
here is what I am doing
[imagesList addObject:[UIImage imageNamed:#"b.png"]];
after executing this line I noticed that the number of objects remains 0
any reason ?
Thanks
I repeate this code in several areas :
Globally I declare :
NSMutableArray *imagesList;
NSUserDefaults *imagesHistory;
in my viewdidload method I write:
imagesHistory=[NSUserDefaults standardUserDefaults]; //imagesHistory is created globallt as NSUserDefault imagesHistory
[imagesHistory setObject:imagesList forKey:#"images history"];
UIImage *image;
image=[UIImage imageNamed:#"b.png"];
[imagesList addObject:image];
imagesHistory=[NSUserDefaults standardUserDefaults];
[imagesHistory setObject:imagesList forKey:#"images history"];
and in the didFinishLaunchingWithOptions I write : (even though I don t need to do it when I am adding strings ...)
imagesList = [[NSMutableArray alloc] init];
Regardless of whether it is a global variable or not, you still need to call alloc and init SOMEWHERE for the object. If you intend to use it throughout your app, then appDidFinishLaunchingWithOptions is a decent place to add this call:
imagesList = [[NSMutableArray alloc] init];
Is your empty array being retained? If you're not using Automatic Reference Counting, there's a good chance you're initializing the array with the following
imagesList = [[NSMutableArray alloc] init];
but it's not being retained. You'll want to retain the empty array so it gets appended to further on in your code.
imagesList = [[[NSMutableArray alloc] init] retain];
Just don't forget to release the array when you're all done with it, in viewDidUnload or wherever is appropriate.
You're allocating/initing imagesList AFTER you try to add an object. You need to alloc/init imageList before you add anything to it.
To make sure it's there, try something like this:
if (!imagelist) imageList = [[NSMutableArray alloc] init];
If it exists, and you're still having this problem, it's possible that you're allocating/initing a new NSMutableArray and assigning it to imageList after you've added the object. This means the old array would be discarded and you'd be left with a new array with zero items.
try UIImageView *image;
image=[UIImage imageNamed:#"b.png"];
also, in #property(nonatomic,retain) use 'strong' instead of 'retain'
I am trying to store user input text (in this case a book title) into an array so that I can output it in a table view in another xib.
I'm getting stuck trying to store the "bookTitle.text" info into my "userinfoArray". I know it probably has a simple solution and I know how to do it in C++ but not in Objective-C. Any tips, links etc. would be great.
NSMutableArray *userinfoArray = [[NSMutableArray alloc]init];
NSString *tempString = [[NSString alloc]initWithString:[bookTitle text]];
[userinfoArray addObject:tempString];
you can then access it later with:
[userinfoArray objectAtIndex:0];
NSMutableArray is very flexible. with addObject:object you can add as many things as you want, remove them with removeObjectAtIndex:index.
more here: NSMutableArray Class Reference
alternatively if you know what size your array will have you can use a normal NSArray: NSArray Class Reference which will work similar
sebastian
Try
userinfoArray = [NSArray arrayWithObject:[bookTitle text]];
Or if you want to create a longer array with more objetcs then
userinfoArray = [NSArray arrayWithObjects:[bookTitle text], secondObject, thirdObject, nil];
If you want to add or remove objects later then you may want to use NSMutableArray instead.
If this does not answer your question, then please try to be a bit more specific about your problem.
I'm working with the MKMapView and I'm using some arrays to handle the title of points on the map
NSString *mapTitles = #"title1^^title2^^title3^^title4";//this data changes between views
NSArray * titlesArray = [mapTitles componentsSeparatedByString: #"^^"];
NSMutableArray * maptitle = [NSMutableArray arrayWithCapacity:[titlesArray count]];
[maptitle addObjectsFromArray:titlesArray];
When a user navigates to another page I want to clear the NSMutableArray so that when they come back to the map I can refresh it with new data. However as the NSMutableArray is getting populated by an NSArray which I can't clear, how do I ensure that the NSMutableArray only gets populated by new data as opposed to something that the NSArray may have kept from the previous view?.
Is it simply a case of releasing the NSArray, for example in viewWillDisappear?
Thanks
You can still clear the mutable array itself:
[mapTitle removeAllObjects];
You shouldn't release the titlesArray because it's autoreleased.