I'm learning Objective-c and made a little practice app to take input from an NSSlider and set the level to it. However, I would like to know if there is any way to make the level indicator update with the dragging of the slider. Currently, it only updates when I let go of the slider. I saw a couple of references to a setContinuous method, but it didn't seem to do anything. If that method is completely unrelated, please constrain your laughter. Also, it would be awesome if you could add code snippets to show me where to put the method.
-setContinuous: should do the trick, if you're sending it to the right object. Or, if you've set up your interface in a .xib file, check the 'continuous' box (I don't remember the actual label) for the slider.
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A Tale of Two Subclasses
By Ben Stock
Prologue
I'm in the process of making a really nice looking set of controls which automatically change their appearance depending on the type of window they're used in (e.g. If you drop a button in a normal window, it looks like any other standard Aqua button. If you drop it on an NSPanel with a window mask of NSHUDWindowMask, however, it'll automatically switch its style to look good on a HUD background. So far, I've subclassed NSButton, NSTextField, NSSlider, and NSSearchField. Last night I started on NSTabView, only to be slammed down by its lack of customizability. It's a real pain in the ass, but I'm a developer, so I'm used to finding my own way. The first thing I think to do is add an instance of NSSegmentedControl in place of the private tabs used by NSTabView. So far, so good. I've got the buttons selectable, they automatically update when new NSTabViewItem's are added, and they work just like the real thing.
And the Pain Begins …
Finally, I start to style my segments, and … WTF have I gotten myself into‽ I should've just gone into acting or something. Objective-C development is slowly taking years off my life. No matter what I do, the "tracking areas" used by NSSegmentedCell don't seem to be updating when my segment widths change. So when my widths change, my artwork does, too. However, the actual tracking area doesn't update (even when I override -updateTrackingAreas. It's really hard to explain, so I decided to draw my segment rectangles behind and in front of the ones drawn by super in -drawSegment:inFrame:withView. Here's a screenshot with my art drawn on top of the underlying tracking areas:
And here's super's implementation above my segment rects:
I've tried overriding everything I can think of. Here are a few of the methods I've overridden (and un-overridden):
-cellSize (NSSegmentedCell)
-cellSizeForBounds: (NSSegmentedCell)
-sizeToFit (NSSegmentedControl)
-intrinsicContentSize (NSSegmentedControl)
-setWidth:forSegment: (NSSegmentedControl/Cell)
-startTrackingAt:inView: (NSSegmentedCell)
-continueTracking:at:inView: (NSSegmentedCell)
-stopTracking:at:inView:mouseIsUp: (NSSegmentedCell)
At this point, some of those methods in the above list are still using my overrides and some aren't. I've mixed and matched, deleted, simplified, rewrote, and refactored, and no matter what I do, the underlying rectangles don't change. I love Apple as much as the next guy, but their view of customization needs to change. I can't stand not being able to understand what's going on in the implementation of all these stupid controls. Not to mention the fact that I still can't fully wrap my head around Auto Layout (which is about the most un-"auto" thing I've ever dealt with), but that's a post for another day. Anyway, if anybody could help a brotha out, I'd be super grateful. Sorry for ranting and thanks for reading!
P.S. None of these things are finished, so please don't be too hard on a few pixel imperfections. ;-)
I would like to build something similar to the code-completion feature in Xcode 4. (The visual style and behavior, not the data structure type work required for code completion).
As the user is typing, a pop-up window presents other word choices that can be selected.
The Feature in action:
I'm not exactly sure where to start. I am mainly concerned with the visual appearance of the window and how I should populate the list with a given set of words. Later I will get into making the window follow the cursor around the screen and etc.
I am mainly looking for an overview of how to display such data in a "window", and how to cusomize the appearance of the thing so it looks like a nice little informational popup rather than a full-on OS X window.
Just add a subview to your current view that happens to be a tableview. Programmatically cause it to be visible on an event (such as mouseDown), and adjust it's position based on where you want it. You will need to instantiate the proper delegate/datasource methods, but it should be pretty straight forward. You will also need a source for the words you want to use in your autocomplete, and put them in an array or something for your tableview datasource to go through.
Like I said, it's not terribly hard, provided you are comfortable using tableviews and adding views to your existing view. If this doesn't explain enough, leave a comment and I can flesh this comment out more.
Add a (completions) subview to your view and set its visible property to NO. Create a separate AutoComplete object that includes the subview as a property and fills it with potential completions. Your controller can respond to key pressed (key typed) events and give the last word (substring the text from the end to the 1st preceding blank) to the AutoComplete on each event. The basic logic in AutoComplete could be something like:
Given an AutoComplete with a list of known words "dog, spaghetti, minute, horse, spare, speed"
When asked to complete a fragment "sp"
Then the following words should be offered as potential completions, "spaghetti, spare, speed"
Which would imply that you need to instantiate it with a list of words (this could be done in the init of your controller), and create a method "-(NSArray*) completeFragment:(NSString*)fragment;". You could drop this into an OCUnit test case and iterate over your implementation of autocomplete until you get it right. You would then write a method that takes the completions from AutoComplete and lists them in the subview. Even better you might create currentWord and potentialCompletions properties in AutoComplete that gets updated as you send it "newFragment:(NSString*)fragment;" messages. Throw that into OCUnit and work it out then use that potentialCompletions property to drive updated of a the subview (which is probably best modeled as a custom tableView).
I'm trying to learn objective-c by making a GUI application using Xcode 3. I'm wondering if it is possible to change the text of a button outside of a tab view depending on which tab in the tabview is selected? As I said I am trying to learn objective-c so please act as though I know next to nothing in your answer. I should probably mention that I tried making a NSObject and tried to define an IBAction in a .h and .m file but that didn't seem to work. (I have tried setting some breakpoints in those files none of which were ever reached leading me to think something isn't wired the way think it is.)
Sorry for the long winded explanation.
Thanks for all the help!
I actually figured it out. What I needed was object delegation, this page, and of course Google to help get the correct syntax for the actual implementation.
UPDATE: With the blush of shame I discovered that the order had nothing to do with the speed of tapping. I was calling the visual code before the super touchesEnded:withEvent call, which was why if you tapped really fast, the display never got a chance to draw the highlighted state before being dismissed again. Because the code that was actually causing the main thread to block just a few milliseconds, the highlighted state would stay visible until the main thread unblocked again, where as if you tapped really fast, it looked like nothing happened at all. Moving the super call up to the top of the overridden method fixed it all. Sorry, if any moderator sees this post it can be deleted. shame
This problem must have been asked a 1000 times at SO, yet I can't find the explanation to match my specific issue.
I have a UIButton subclass with a custom design. Of course the design is custom enough that I can't just use the regular setSomething:forControlState: methods. I need a different backgroundcolor on touch, for one, and some icons that need to flash.
To implement these view changes, I (counter-intuitively) put the display code in (A) touchesBegan:withEvent and (Z) touchesEnded:withEvent:, before calling their respective super methods. Feels weird, but it works as intended, or so it seemed at first.
After implementing addTarget:action:forControlEvents was used to bind the UIControlEventTouchUpInside to the method (X) itemTapped:, I would expect these methods to always fire in the order (A)(X)(Z). However, if you tap the screen real fast (or the mouse in simulator), they fire in the order (A)(Z)(X). Where (A) and (Z) follow each other in such rapid succession, that the whole visual feedback for tapping is invisible. This is unwanted behavior. This also can't be the way to go, for so many apps need similar behavior, right?
So my question to you is: What am I doing wrong? One thing I'm guessing is that the visual appearance of the buttons shouldn't be manipulated in the touchesBegan:withEvent and touchesEnded:withEvent, but then where? Or am I missing some other well known fact?
Thanks for the nudge,
Eric-Paul.
I don't know why the order is different, but here's 2 suggestions to help deal with it.
What visual changes are you making to the button? If it's things like changing title/image/background image, you can do all this by modifying the highlighted state of the button. You can set a few properties like title and background image per-state. When the user's finger is down on the button, the highlighted state is turned on, so any changes you make to this state will be visible at this time. Do note that if you're making use of the selected state on the button, then you'll need to also set up the visual appearance for UIControlStateHighlighted|UIControlStateSelected, otherwise it will default back to inheriting from Normal when both highlighted & selected are on.
The other suggestion is to ditch touchesBegan:withEvent: and touchesEnded:withEvent: and switch over to using the methods inherited from UIControl, namely beginTrackingWithTouch:withEvent: and endTrackingWithTouch:withEvent:. You may also want to implement continueTrackingWithTouch:withEvent: and use the touchInside property to turn off your visual tweaks if the touch leaves the control.
I'm slowly learning Objective-C and Cocoa, and the only way I see so far to capture key events in Text Views is to use delegation, but I'm having trouble finding useful documentation and examples on how to implement such a solution. Can anyone point me in the right direction or supply some first-hand help?
Generally, the way you implement it is simply to add the required function to your view's controller, and set its delegate. For example, if you want code to run when the view loads, you just delegate your view to the controller, and implement the awakeFromNib function.
So, to detect a key press in a text view, make sure your controller is the text view's delegate, and then implement this:
- (void)keyUp:(NSEvent *)theEvent
Note that this is an inherited NSResponder method, not a NSTextView method.
Just a tip for syntax highlighting:
Don't highlight the whole text view at once - it's very slow. Also don't highlight the last edited text using -editedRange - it's very slow too if the user pastes a large body of text into the text view.
Instead you need to highlight the visible text which is done like this:
NSRect visibleRect = [[[textView enclosingScrollView] contentView] documentVisibleRect];
NSRange visibleRange = [[textView layoutManager] glyphRangeForBoundingRect:visibleRect inTextContainer:[textView textContainer]];
Then you feed visibleRange to your highlighting code.
It's important to tell us what you're really trying to accomplish — the higher-level goal that you think capturing key events in an NSTextView will address.
For example, when someone asks me how to capture key events in an NSTextField what they really want to know is how to validate input in the field. That's done by setting the field's formatter to an instance of NSFormatter (whether one of the formatters included in Cocoa or a custom one), not by processing keystrokes directly.
So given that example, what are you really trying to accomplish?
I've done some hard digging, and I did find an answer to my own question. I'll get at it below, but thanks to the two fellas who replied. I think that Stack Overflow is a fantastic site already--I hope more Mac developers find their way in once the beta is over--this could be a great resource for other developers looking to transition to the platform.
So, I did, as suggested by Danny, find my answer in delegation. What I didn't understand from Danny's post was that there are a set of delegate-enabled methods in the delegating object, and that the delegate must implement said events. And so for a TextView, I was able to find the method textDidChange, which accomplished what I wanted in an even better way than simply capturing key presses would have done. So if I implement this in my controller:
- (void)textDidChange:(NSNotification *)aNotification;
I can respond to the text being edited. There are, of course, other methods available, and I'm excited to play with them, because I know I'll learn a whole lot as I do. Thanks again, guys.