I'm having trouble dealing with pointers in Objective-C. Basically, I have the following structure in my class :
UITableView *list;
NSArray *objArray;
UIPickerView *pickerCtrl;
My "list" shows the data contained in objArray, which is a temporary structure linking to custom NSObjects of various types (not stored in my current object).
Choosing one element in the list shows the "pickerCtrl", displaying appropriate data depending on which TableView line is currently selected.
My goal is to replace oldObject's data (the external object, accessed by objArray) with newObject's data (selected in the PickerView). Like this :
- (void)pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
id oldObject = [objArray objectAtIndex:[[list indexPathForSelectedRow] row]];
id newObject = [pickerData objectAtIndex:row];
*oldObject = *newObject;
}
From the debugger, oldObject and newObject both have the right memory addresses. The problem is, no assignation seems to be done, and the old data is never replaced by the data from "newObject".
What am I missing here ?
This is not the proper way to deal with mutable arrays, you are thinking too low-level.
Rather, try this:
[objArray removeObject:oldObject];
[objArray addObject:newObjec];
You can also use the insertObject:atIndex: method. See the reference for NSMutableArray for further information
Use:
- (void)exchangeObjectAtIndex:(NSUInteger)idx1 withObjectAtIndex:(NSUInteger)idx2
Example:
[objArray exchangeObjectAtIndex:[[list indexPathForSelectedRow] row],row];
Related
Using cocoa on mac osx 10.7 I populated a TableView with some rows, I have some confusions,
names is an NSArray* containing NSString*
- (id)tableView:(NSTableView *)aTableView objectValueForTableColumn:(NSTableColumn *)aTableColumn row:(NSInteger)rowIndex;
{
return [names objectAtIndex:rowIndex];
}
I checked the protocol reference for the datasource in the apple's documentation
https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ApplicationKit/Protocols/NSTableDataSource_Protocol/Reference/Reference.html
I am returning an NSString* in the above function, the signature of the method only returns id and not NSString* . The documentation gave me no clue about the return type it just says
An item in the data source in the specified tableColumn of the view.
My case was simple NSString* made sense and it worked but I am not sure. I am wondering where is this implicit knowledge coming from as to what type of data has to be returned by this method given there is no mention in the signature and nothing in the method's documentation :/
Any advise ? I am coming from .Net/android/ background the documentations there made more sense probably because those are strongly typed lanuguages ,...
The type of object that you should return is based on how the cells in your NSTableView are defined. By default when you create an NSTableView in Interface Builder, the cells are defined as NSTextFieldCell, so can return an NSString for those cells. However you can define the cells to accept other types of objects in your code (for example NSImageCell, NSButtonCell, etc).
I am having trouble using the new Lion functionality to rearrange rows in my app. I am using outlineView:pasteboardWriterForItem: to store the row indexes so that I can access them later when I validate/accept the drop. I create a new NSPasteboardItem to return, and am attempting to store the row number as so:
[pbItem setData: [NSKeyedArchiver archivedDataWithRootObject: [NSNumber numberWithInteger: [fTableView rowForItem: item]]]
forType: TABLE_VIEW_DATA_TYPE];
TABLE_VIEW_DATA_TYPE is a custom string I'm using to distinguish my custom data in the dragging pasteboard. I don't use it outside of dragging these rows.
When attempting the drag, I receive in Console: 'TableViewDataType' is not a valid UTI string. Cannot set data for an invalid UTI.
Of course I could use some of the built-in UTIs for pasteboards, but none of them apply (and using them causes the drag to accept drags other than the rows, which it shouldn't). Is there something I'm missing, like a way to define a custom UTI just for dragging (without making it a "real" UTI since I have no use for it outside of the internal dragging, so it shouldn't be public).
Thanks for any help!
I had similar requirements except I had a grid of objects that I wanted to rearrange by dragging selected objects to a new location. There are several ways of doing this, including creating a custom object and implementing the NSPasteboardWriting and NSPasteboardReading protocols, (and NSCoding protocols if you will be reading data as NSPasteboardReadingAsKeyedArchive), but this seems to be overkill for dragging of objects that remain internal to the application.
What I did involves using the NSPasteboardItem as a wrapper with a custom UTI type (it already implements the NSPasteboardWriting and NSPasteboardReading protocols). First declare a custom UTI type:
#define kUTIMyCustomType #“com.mycompany.MyApp.MyCustomType”
This needs to be defined in the ‘com.domain.MyApp’ format otherwise you will get errors of the form: “XXX is not a valid UTI string. Cannot set data for an invalid UTI.” Apple mentions this in their documentation.
Then you must register this custom UTI type in the view in which your dragging will occur. This can be done at runtime, and does not require any .plist additions. In your view's init method add the following:
[self registerForDraggedTypes:[NSArray arrayWithObjects:(NSString *)kUTIMyCustomType, nil]];
Now, make sure that the delegate is set for this view, and the delegate object implements the required NSDraggingSource and NSDraggingDestination protocol methods. This will allow you to avoid breaking the MVC design pattern, by allowing the designated controller object to handle placing the data on the pasteboard which will likely involve querying model data (i.e., indexes).
Specifically, for placing on the dragging pasteboard the indexes of objects to be moved when dragging begins as NSPasteboardItem wrappers of your index data:
- (void) draggingSession:(NSDraggingSession *)session willBeginAtPoint:(NSPoint)screenPoint
{
NSPasteboard * pboard = [NSPasteboard pasteboardWithName:NSDragPboard];
[pboard clearContents];
NSMutableArray * selectedIndexes = [NSMutableArray array];
// Add NSString indexes for dragged items to pasteboard in NSPasteboardItem wrappers.
for (MyModel * myModel in [self selectedObjects])
{
NSPasteboardItem * pasteboardItem = [[[NSPasteboardItem alloc] init] autorelease];
[pasteboardItem setString:[NSString stringWithFormat:#"%#", [myModel index]]
forType:kUTIMyCustomType];
[selectedIndexes addObject:pasteboardItem];
}
[pboard writeObjects:selectedIndexes];
}
And when the dragging operation completes, to read the dragged index NSPasteboardItem data:
- (BOOL) performDragOperation:(id <NSDraggingInfo>)sender
{
NSPasteboard * pasteboard = [sender draggingPasteboard];
// Check for custom NSPasteboardItem's which wrap our custom object indexes.
NSArray * classArray = [NSArray arrayWithObject:[NSPasteboardItem class]];
NSArray * items = [pasteboard readObjectsForClasses:classArray options:[NSDictionary dictionary]];
if (items == nil)
return NO;
// Convert array of NSPasteboardItem's with NSString index reps. to array of NSNumber indexes.
NSMutableArray * indexes = [NSMutableArray array];
for (NSPasteboardItem * item in items)
[indexes addObject:[NSNumber numberWithInteger:[[item stringForType:kUTIMyCustomType] integerValue]]];
//
// Handle dragged indexes…
//
return YES;
}
Another technique you can use is to just store the indices of the objects you're dragging in an instance variable on the side. Putting everything on the pasteboard isn't strictly necessary unless you're accepting items from another app or vice versa.
In awakeFromNib, register for the NSStringPboardType.
In …pasteboardWriterForRow, return [NSString string].
In …draggingSession:willBegin…, set your instance variable to the indices you want to track.
In validateDrop, return NSDragOperationNone if your instance variable is nil or the view is not yours.
In …draggingSession:ended…, nil out your instance variable.
Hope that helps… I'm using the technique for a table view, but it should be virtually identical for an outline view.
Instead of using a vanilla NSPasteboardItem, you should create a custom object that conforms to the NSPasteboardWriting protocol.
In your custom object, you can implement writableTypesForPasteboard: to return a list of custom UTIs that your pasteboard item supports. You then implement pasteboardPropertyListForType: to return a plist representation of your object for the appropriate custom UTI when the pasteboard asks for it.
You can create a plist from arbitrary data using the +propertyListWithData:options:format:error: method of NSPropertyListSerialization.
You would then override tableView:pasteboardWriterForRow: in your table view data source to return an instance of your custom object.
I'm making this program that has an NSTableView with four columns, two of which are make of checkboxes. I'm only trying to get one working right now and I've gotten stuck.
First, here's my relevant code:
- (NSInteger)numberOfRowsInTableView:(NSTableView *)aTableView {
NSString *filePathThree = [[NSBundle mainBundle] pathForResource:#"mydictionary" ofType:#"plist"];
NSData *myDataThree = [[NSData alloc]initWithContentsOfFile:filePathThree];
self.flozzCodeAndName = (NSMutableDictionary *)[NSPropertyListSerialization
propertyListFromData:myDataThree
mutabilityOption:NSPropertyListMutableContainersAndLeaves
format:NULL
errorDescription:NULL];
return [[flozzCodeAndName objectForKey:#"name"] count];
}
- (void)tableView:(NSTableView *)tableView
setObjectValue:(id)anObject forTableColumn:(NSTableColumn *)tableColumn row:(NSInteger)rowIndex
{
NSButtonCell *cell;
cell = [[NSButtonCell alloc] init];
[cell setButtonType:NSSwitchButton];
[cell setTitle:#""];
[cell setTag:rowIndex];
NSLog(#"%d", [cell tag]);
[cell setCellAttribute:NSCellEditable to:3];
[cell setImagePosition:NSImageOnly];
[cell setState:NSOnState];
NSLog(#"%d", [cell state]);
[havzColumn setDataCell:cell];
[myTableVeew reloadData];
[cell release];
}
- (id)tableView:(NSTableView *)aTableView
objectValueForTableColumn:(NSTableColumn *)aTableColumn row:(NSInteger)rowIndex {
NSString *filePathThree = [[NSBundle mainBundle] pathForResource:#"mydictionary" ofType:#"plist"];
NSData *myDataThree = [[NSData alloc]initWithContentsOfFile:filePathThree];
self.flozzCodeAndName = (NSMutableDictionary *)[NSPropertyListSerialization
propertyListFromData:myDataThree
mutabilityOption:NSPropertyListMutableContainersAndLeaves
format:NULL
errorDescription:NULL];
NSArray *myArray = [flozzCodeAndName objectForKey:[aTableColumn identifier]];
NSString *myStringValue = [myArray objectAtIndex:rowIndex];
return myStringValue;
}
As you can see, I'm using the data source method for this table rather than bindings. The book I read for Cocoa made some checkboxes with tags, but I think they were in an array, so that might not be the best thing to do.
Anyway, when I run this, the debugger will show me the tag (which equals the row) along with the state of the button (1 for all of them because of NSOnState). My problem is that I cannot get the boxes to check and uncheck depending on their state. I read this question: Checkbox on table column won't register click
And then the NSTableView datasource reference. According to Mr. Nozzi in the linked question, it seems to me that an array containing the states for the boxes is needed, so I tried that, setting [cell state] to an NSNumber to get it into an NSMutableArray. I FUBAR'd that and don't think that was right. There are 454 rows in this table (tags go to 453 because of arrays starting at 0), for all four columns.
I also wonder if I should put the cell definition stuff that is in tableview:setObjectValue: into an 'awakeFromNib'. I did put a checkbox button cell in the IB, but I was having problems with it earlier, so I decided to do it programmatically too. During all of these, I did, and still do, have a [myTableVeew reloadData] in the setObjectValue method.
The assistance is appreciated, if any other info is needed, I can get it.
You have two problems: Your data source keeps getting blown away and you're not using the ...objectValue... method properly.
Data Source:
You're blowing away your data source in your -numberOfRowsInTableView: method and replacing it every time the table needs to do a refresh. You'll want to cache (a mutable copy of) your dictionary only when you need to (like at application launch) then only refer to it from the table data source methods. Perhaps you should move it to an instance variable and use proper accessors.
Also, the documentation mentions that, because the data source methods are called very frequently, they should be fast, so from a performance viewpoint alone this is not a good idea. You should only do what it takes to answer the question the delegate method is posing to keep the table responsive with large data sets.
Object Value: You should ONLY be returning the object value from this method (usually an NSNumber object containing the state the checkbox is meant to toggle.
You should set your table column's -dataCell when the view is loaded or at application launch. Even easier: drag a check box cell into the table column in Interface Builder to set that as the data cell without code.
Additional Observation: If you plan to persist the changes to this information in any way, note that you must never rely on the application bundle being writable and should never attempt to overwrite resource files like the one you're loading from your bundle. You'll need to save the information elsewhere, using your bundle copy as a template copy only.
I am just learning how to setup a multiple picker and I am a little curious about the two labeled sections below:
// METHOD_001
NSInteger row_001 = [doublePicker selectedRowInComponent:0];
NSInteger row_002 = [doublePicker selectedRowInComponent:1];
NSString *selected_001 = [pickerData_001 objectAtIndex:row_001];
NSString *selected_002 = [pickerData_002 objectAtIndex:row_002];
EDIT_001:
Maybe if I simplify this a little .... I know what METHOD_001 is doing, but what about the method below. If I comment it out my code still runs but the picker UI does not get populated with my data, so its obviously involved in taking data from the dataSource so the picker can display it. One puzzling aspect is that it uses "objectAtIndex:row" to access an item, even though the whole UI needs populating (i.e. all the rows) Does this then mean that this gets called for each row, seems funny that it does not take a NSArray nd populated the picker UI in one shot?
// DELEGATE
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
if(component == kCoffeeIndex) return [pickerData_001 objectAtIndex:row];
return [pickerData_002 objectAtIndex:row];
}
gary
The delegate method -pickerView:titleForRow:forComponent: will be called every time the UI thinks the data is needed.
It doesn't take an array because the titles may be generated dynamically or retrieved lazily. It's actually the same story for table views. Usually only the visible rows will be loaded, to reduce the data required.
I am working on an app that is not core data based - the data feed is a series of web services.
Two arrays are created from the data feed. The first holds season data, each array object being an NSDictionary. Two of the NSDictionary entries hold the data to be displayed in the popup ('seasonName') and an id ('seasonID') that acts as a pointer (in an external table) by matches defined for that season.
The second array is also a collection of NSDictionaries. Two of the entries hold the data to be displayed in the popup ('matchDescription') and the id ('matchSeasonId') that points to the seasonId defined in the NSDictionaries in first array.
I have two NSPopUps. I want the first to display the season names and the second to display the matches defined for that season, depending on the selection in the first.
I'm new at bindings, so excuse me if I've missed something obvious.
I've tried using ArrayControllers as follows:
SeasonsArrayController:
content bound to appDelegate seasonsPopUpArrayData.
seasonsPopup:
content bound to SeasonsArrayController.arrangedObjects; content value bound to SeasonsArrayController.arrangedObjects.seasonName
I see the season names fine.
I can obviously follow a similar route to see the matches, but I then see them all, instead of restricting the list to the matches for the season highlighted.
All the tutorials I can find seem to revolve around core data and utilise the relationships defined therein. I don't have that luxury here.
Any help very gratefully received.
This is not an answer - more an extension of the previous problem.
I created MatchesArrayController and subclassed it from NSArrayController to allow some customisation.
Following the example in 'Filtering Using a Custom Array Controller' from 'Cocoa Bindings Topics', I followed the same idea as above:
MatchessArrayController: content bound to appDelegate matchesPopUpArrayData.
matchesPopup: content bound to MatchesArrayController.arrangedObjects; content value bound to MatchesArrayController.arrangedObjects.matchDescription.
I've derived the selected item from seasonPopUp:sender and used this to identify the seasonId.
The idea is to change the arrangedObjects in MatchesArrayController by defining the following in;
- (NSArray *)arrangeObjects:(NSArray *)objects
{
if (searchString == nil) {
return [super arrangeObjects:objects];
}
NSMutableArray *filteredObjects = [NSMutableArray arrayWithCapacity:[objects count]];
NSEnumerator *objectsEnumerator = [objects objectEnumerator];
id item;
while (item = [objectsEnumerator nextObject]) {
if ([[[item valueForKeyPath:#"matchSeasonId"] stringValue] rangeOfString:searchString options:NSAnchoredSearch].location != NSNotFound) {
[filteredObjects addObject:item];
}
}
return [super arrangeObjects:filteredObjects];
}
- (void)searchWithString:(NSString *)theSearchString {
[self setSearchString:theSearchString];
[self rearrangeObjects];
}
- (void)setSearchString:(NSString *)aString
{
[aString retain];
[searchString release];
searchString=aString;
}
I've used NSLog to check that things are happening the way they are supposed to and all seems ok.
However, it still doesn't do what I want.
[self rearrangeObjects]; is supposed to invoke the arrangeObjects method but doesn't. I have to call it explicity
(i.e.[matchesArrayController arrangeObjects:matchesPopUpArrayData]; )
Even then, although filteredObjects gets changed the way it is supposed to, the drop down list does not get updated the way I want it to.