This is driving me a bit crazy..
Down below is a screenshot of my program so far.
On the right is an NSTableView (view-based). This is where the user can select a document they want to work on.
On the left is the NSTextView. Text will be displayed depending on what item they choose in the NSTableView.
There are also big plus and minus buttons for creating/deleting new items in the tableview.
Simple right? I wish.
Right now I have it so the tableview gets data from a mutable array. The mutable array contains objects of a class called DocumentItem. The DocumentItem just has two strings, one for the document text and one for the document title.
What works so far:
When I manually add objects to the array using code, I am able to freely switch through the documents and the textview will update accordingly.
What doesn't work:
When the user switches to a different document, I want to call the NSTableView replaceObjectAtIndex method save the changes that they have made to the object in the array.
How my code works so far:
The mutable array is stored in a data class. The data class is a shared class and is referred to in my code as theDATA.
I have a thread looping in my class that has the textview. In my tableview class I have a method called blastToScreen that will change a BOOL called shouldBLAST to YES.
Here is the code in my TableController class to set the BOOL to YES:
- (void) blastToScreen{
theDATA.blasttext = [[theDATA.globaldoclist objectAtIndex:[tablevieww selectedRow]] doccontents];
theDATA.shouldBLAST=YES;
}
Here is the shouldBLAST method in my looped thread(in a different class from the textview). Please note that the if-statement that says if(theDATA.switchedrow) is there to make sure that certain code gets runned only when a user switches their row in the tableview.
if(theDATA.shouldBLAST){
if(theDATA.switchedrow){
DocumentItem * itemr = [theDATA.globaldoclist objectAtIndex:theDATA.lastindex];
NSLog(#"(%li) prev content - >%#",(long)theDATA.lastindex,itemr.doccontents);
itemr.doccontents=textvieww.string;
NSLog(#"(%li)adding content - > %# <- to %#",theDATA.lastindex, itemr.doccontents,itemr.docname);
theDATA.switchedrow=NO;
[theDATA.globaldoclist replaceObjectAtIndex:theDATA.lastindex withObject:itemr ];
NSLog(#"changed: - > %#",[[theDATA.globaldoclist objectAtIndex:theDATA.lastindex] doccontents]);
}
textvieww.string=theDATA.blasttext;
theDATA.shouldBLAST=NO;
NSLog(#"changed: - > %#",[[theDATA.globaldoclist objectAtIndex:theDATA.lastindex] doccontents]);
theDATA.lastindex=theDATA.selectedrow;
}
Here's the weird part about all this:
According to the NSLog statements I set up, my code works for a split second and then resets.
Down below is what the console says. ignore the (0). that is just talking about the last selected index.
What it is saying is that the text before switching was nothing(fine). It is saying that it is adding the text "Potato" to that array(still fine). Then, the first time I fetched the object from the array it shows that it successfully changed to "Potato"(Still fine). Then when I tried to fetch the SAME exact data a few lines later, it returned nothing. :(
I feel like the issue resides somewhere in my TableController class. Here's a link to the code in my TableController class.
Here's what the console returned:
2015-09-14 17:17:46.024 Simplicity[4801:432580] (0) prev content - >
2015-09-14 17:17:46.025 Simplicity[4801:432580] (0)adding content - > Potato <- to Untitled
2015-09-14 17:17:46.025 Simplicity[4801:432580] changed: - > Potato
2015-09-14 17:17:46.025 Simplicity[4801:432580] changed: - >
I really hope you guys can help me. I tried pretty much everything I could to solve this issue.This is holding me back from finishing my software.
Probably, the doccontents property of your DocumentItem class is strong (or retain) when it should be copy.
From the docs for the string property of NSText (from which NSTextView inherits):
For performance reasons, this method returns the current backing store of the text object. If you want to maintain a snapshot of this as you manipulate the text storage, you should make a copy of the appropriate substring.
So, if you're just keeping a reference to that same object, when the text view's content is changed, the content of the object you've got a reference to also changes. You need to make a private copy.
Related
I'm implementing a search screen in my app using UITableViewDiffableDataSource. Each cell represents a search hit and highlights the search match in the cell title, kind of like Xcode's Open Quickly window highlights portions of its result items. As text is typed into the search field, I update the results list. Results move up and down in the list as their relevance changes.
The trick is that I need to force every cell to re-render every time the search text changes, because a new search string means an update to the highlighted portions of the cell title. But I don't want to animate a deletion and insert, because it's still the same item. How can I tell the data source using the snapshot that it needs to reload cells?
I declare the data source like this:
#property (retain) UITableViewDiffableDataSource<NSString *, SearchHit *> *dataSource;
SearchHit represents one search result; it has properties for a display title and an array of ranges to highlight in the title. And it overrides hash and isEqual: so that every result row is uniquely identified.
My code looks something like this:
-(void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
{
NSArray<SearchHit *> *hits = [self fetchHits:searchText];
NSDiffableDataSourceSnapshot<NSString *, SearchHit *> *snap = [[[NSDiffableDataSourceSnapshot alloc] init] autorelease];
[snap appendSectionsWithIdentifiers:#[#""]];
[snap appendItemsWithIdentifiers:hits];
[snap reloadItemsWithIdentifiers:hits];
[self.dataSource applySnapshot:snap animatingDifferences:YES];
}
At first I didn't have the reloadItemsWithIdentifiers call there, and then no cell would change at all once it was in the result list. Adding the reload call helped, but now most of the cells are constantly one update behind. This smells like a logic error somewhere in my code, but I've verified that the hits passed to the snapshot are correct and the hits passed to the data source's cell creation callback are not.
This article by Donny Wals and this related Twitter thread involving Steve Breen suggests that the way to fix this is to make the item identifier type only represent the properties needed to display the cell. So I updated SearchHit's hash and equality comparison to include the highlighted portions of the title, which they didn't before. Then I got delete and insert animations for all the cells on every update, which I don't want.
This seems like what reloadItemsWithIdentifiers should do...right?
Sample project here on GitHub.
The diffable datasource API may not be the right tool to effect animations on cells themselves. It’s geared towards the animation of the appearance, disappearance and ordering of cells. If your data source has a change that is expressed via Hashable conformance the api will see it as a change and delete/insert etc.
My advice would be to remove the search text from the item identifier and have each cell observe the search text and effect an animation or redraw independently from the datasource.
The proper solution to this is actually in the names of the APIs - the objects you give to the data source should be identifiers, like rowid values from a database. In my case, when the item identifiers don't represent rows in a database that I can look up, I just need to keep the state of the objects in some sort of lookup structure, so that when I call reloadItemsWithIdentifiers, I get the state for each cell from that structure, not from the object that the data source hands to me.
I have six on-screen buttons whose titles need to correspond to six elements in an NSMutableArray, when the value in the array changes, I also need the title to change with it. I am having trouble figuring out how to create that constantly updating line to the button, I'm still quiet new to objective-c development as well as Xcode.
I also need to make sure that when there is no value at that particular index of the array, the button cannot be clicked on
here is an example of one of the buttons
- (IBAction)card1Pressed:(id)sender {
if (self.userHasEnteredFirstNumber) {
if (!self.userHasEnteredSecondNumber) {
self.secondNumber = [sender currentTitle];
}
}
else{
self.firstNumber = [sender currentTitle];
}
}
The end goal is to have the user press two buttons, then chose weather to add, subtract, multiply, or divide them. After they pick one of those four operations, the values that the buttons were assigned to in the array will be removed and replaced with whatever the new number is. So after they do this once there will only be 5 numbers left in the array, then 4, then 3..... and so on.
The numbers will be drawn and added to an NSMutable array titled currentHand
UPDATE: Using UIOutletCollection I linked the buttons to the method like this
the link to the picture is here "sorry about not being able to directly post it but new users must have a reputation of 10 before they can"
link to photo of declaration and implementation with interface-builder of IBOutletCollection
was this correct?
the code for the header file regarding the IBOutletCollection is as follows "please note that this has been connected to the six buttons I want to use it with in interface builder, a picture of it is shown above"
#property (nonatomic,retain) IBOutletCollection (UIButton)NSArray *buttonArray;
the code in the implementation file regarding the IBOutletController is as follows
# synthesize buttonArray = _buttonArray;
You want to use Key-Value observing, check out this from the Apple documentation:
https://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/KeyValueObserving/KeyValueObserving.html#//apple_ref/doc/uid/10000177i
Okay okay, so essentially you have a 'Button'-Array, whose 'Caption' is served by a NSMutableArray, which can easily be changed around, correct?
Now, this is only how I'd do it, there may be better solutions out there, but here goes:
You need a 'change' interface, which is called EACH time, something happens to your NSMutableArray. For example (since I don't know WHAT exactly is in that array of yours):
- (void) ChangeArray:(int)IDofElement (NSString *)newValue {
[arr replaceObjectAtIndex:IDofElement withObject:newValue]; //Updates/Empties the indexed Element.
if(newValue != nil) {
[buttons[IDOfElement] setText:newValue];
}
buttons[IDOfElement].enabled = (newValue != nil); //Makes Button 'clickable'
}
Like this, each time the value inside that array of yours gets changed, the corresponding caption also gets updated. Of course you would need an array of the buttons for this to work, but I don't think that's the big problem.
Another possible solution: Save a reference to the button inside of the object that's stored in the array and whenever the value is changed, change the button's caption too.
Does this help? Mind you, this is not the 'perfect solution', but something I'd come up with.
Please also note, that this is just from the top of my head and probably faulty at some points. But it should be able to point you in the general direction.
I've been trying to work out how to use table views and I'm a little stuck if I'm honest. I wanted to use a tableview with a limited number of rows (say 50 max). It starts of empty, with 0 rows. Then I wanted to do something along the lines of:
[self logMessage:#"Waiting for response"];
Which inserts a new row at the bottom with the above text. If I do another call to this pseudo function:
[self logMessage:#"Server response received"];
It should insert yet another new row below the previous row, and ensure it is visible. Once the above limit of 50 is reached, and a new message is inserted, I wanted the oldest message to be removed. All of this would be scrollable, with the latest being visible by default.
Am I looking at the right thing to do this? Eventually, I was hoping to have this in a nice little drawer below the main window, which I can then toggle from the main menu if needed. But as I said, I can't work out how to use a table view properly, it doesn't seem to be as straight forward as other objects are.
Any example code would be greatly appreciated!
Since log viewer is a read-only application of a UITableView, the way you do it is rather straightforward once you understand the basics. Recall that table views rely on their data models to provide them with the correct information that needs to be displayed.
A data model for "the last fifty lines of log" could be as simple as an NSMutableArray: use insertObject:atIndex: to add lines, and removeLastObject to remove the "overflow" lines, like this:
NSMutableArray *logLines = [NSMutableArray array]; // <<== this goes into the init method
-(void) addLogLine:(NSString*)line {
[logLines insertObject:line atIndex:0];
while (logLines.count > 50) {
[logLines removeLastObject];
}
}
Now you can use logLines as your table's "model": the data provider can tell how many lines there are by looking at logLines.count; the content of each row in the table will be the object at the corresponding index in logLines, and so on. Take a look at the UITableView section of your favorite iOs tutorial for the "boilerplate code" that needs to be written in order to display array elements in a UITableView.
I have a tableview. One of the columns in the tableview uses an NSLevelIndicatorCell.
I want to be able to allow the user to edit the warn and critical values for the level indicator such that when they enter a value into a a "warning level" textbox, it changes the warn value of the level indicators being displayed in ALL of the tableview's rows.
I am very much a newbie with Objective-C so all I can figure out so far is that I must need a delegate method to watch the textbox BUT if I succeed in doing that, how on earth do I send the new value to the particular tableview column so that the update happens to ALL of the rows (i.e. how do I send what message to the tableview and target a cell within a column within a tableview)?
Here is the code to the solution I came up with should anyone need it.
- (IBAction)setWarningLevel:(id)sender {
double v;
NSScanner *ns = [NSScanner scannerWithString:[warnLevel stringValue]];
[ns scanDouble:&v];
[levelIndicator setWarningValue:v];
}
This is a textbook case for using Cocoa bindings. Just bind the value of the text field to the NSLevelIndicatorCell in your table view (do that in Interface Builder). The updates should happen automagically.
I think it should apply for all the cells in the table view if you apply the binding to the cell in IB. However if it doesn't, you will need to write a couple lines of code that set up the binding every time a new row in the table is created. That link above will explain everything in detail, but basically you will be setting up a Key-Value Observer relationship in code between the text field and the instance of the level indicator in the row being created.
I think you may have overdone it.
NSTextField subclasses NSControl, so you need to look in the docs for NSControl for a useful function.
Try re-writing it like this; assuming you're taking the value from a warnLevel textfield.
- (IBAction)setWarningLevel:(id)sender {
double v = [warnLevel doubleValue];
[levelIndicator setWarningValue:v];
}
Although this is usually shortened to this;
- (IBAction)setWarningLevel:(id)sender {
[levelIndicator setWarningValue:[warnLevel doubleValue]];
}
You should probably have some validation that the textfield has a valid number. If you're only choosing a couple of numbers have a look at using a stepper control.
Usually, with Cocoa, if you feel like you're jumping through too many hoops, there is sometimes an easier way.
Usually ;-)
I need to keep an NSPathControl updated with the currently selected path in an NSBrowser, but I'm having trouble figuring out a way of getting notifications when the path has changed from the NSBrowser. The ideal way to do this would just to be to observe the path key path in the NSBrowser, but that gives a KVO can only observe set<key> methods which return void message and no updates (setPath returns a bool success value).
I also tried observing the selectedCell key path, but I'm not getting notifications when the selection there is changed.
Is there some other really obvious way to do this that I'm missing?
Courtesy of Rob Keniger over at Cocoa Dev:
Have you looked at the SimpleBrowser
example in /Developer/Examples? It
shows how to get the current selection
when it is changed by the user,
basically by just setting up the
action of the NSBrowser.
That is indeed the way to do it. Just implement a method like - (void)browserClicked: in your controller and map it to the NSBrowser's action in interface builder with whatever you want to happen each time the selection changes inside that method, e.g.
- (void)browserClicked:(id)browser {
self.pathToSelectedCell = [browser path]; // NSPathControl is bound to pathToSelectedCell
}
I just checked in IB, and it looks like NSBrowser has a selection index paths binding (an array of NSIndexPath objects) that you could possibly monitor with KVO. It's strange but I don't see any mention of it in the docs, so you might need to do a little research to see if that's something you should or shouldn't use, even if it seems to work. If it does, in your KVO observation method you would find the browser's current path, and convert that to an NSURL the path control can use.
If that doesn't work there's also the delegate methods - (BOOL)browser:(NSBrowser *)sender selectRow:(NSInteger)row inColumn:(NSInteger)column and - (BOOL)browser:(NSBrowser *)sender selectCellWithString:(NSString *)title inColumn:(NSInteger)column.
As of 10.6, one can find out which items are selected, by using the delegate callback as follows:
- (NSIndexSet *)browser:(NSBrowser *)browser selectionIndexesForProposedSelection:(NSIndexSet *)proposedSelectionIndexes inColumn:(NSInteger)column
{
NSLog(#"New first item of the new selection is at index %#", [proposedSelectionIndexes firstIndex]);
// Do something with the selected index or indicies
return proposedSelectionIndexes; // Allow the selection to occur by not changing this
}