I'm totally new to iOS/objective-c and I got assigned a project to remove a few bugs in an iOS app and add some features.
What I'm trying to do at the moment is sync up a slider which represents a percentage with a newly added text field that can be fine tuned along with the slider. The key is that both are essentially synced up at the same time; if the user changes the slider to 75.2% for example, that same value must show up in the text field - and vice-versa.
I've done a lot of Googling around for this, but haven't been able to find much unfortunately. The class that manages everything is somehow synced up with .xib file. What would be nice to know is how one syncs these two together as well, and sets properties/events in the iOS Interface Builder which somehow effect the class.
So, how do these two aspects of iPhone development work?
I appreciate your time.
Related
I've watched the WWDC 2014 session (#608 "Best practices for building sprite kit games") a couple of times and I just want to clarify the purpose behind using .sks files. Am I supposed to put separate assets into each .sks file? Here's a little bit of background into what I'm doing. I'm creating a Mac app that will text piano students to play chords using a MIDI keyboard. Chords will appear on the screen and they'll play them one by one and get a score. Here's a mockup of what the app may look like. Side note: for those that may know music, we're using the numeric version of chords instead of explicit names like Cm, etc.
Would I have a separate .sks file for each element of the UI. For instance, one for the green timer bar, one for the piano keys, etc. The example that they use in the video is a pretty simple one. I am subclassing SKSpriteNode for the timer and on-screen piano so how would I handle the resources for those. They are not static objects and they will change either over time (timer) or due to user input (keyboard)
I really want to organize my project using best practices. Please help. Thanks in advance.
Sks files are serialized SKScene objects. The intent is to provide something like interface builder for constructing SKScene scenes visually. The common use case is to layout complex backgrounds or levels and define starting positions. You would only have one file per scene in many cases. However you can use the sks files to organize and serialize conceptual components of a scene, as demonstrated in versions of the Apple Adventure sample code released since the sks format and scene editor were introduced with Xcode 6
In the screenshot above, you could organize the project into sections that are fairly generic and reusable, like the keyboard for one file and the hud atop the scene for another file. However, you could put them all in one file, then duplicate the file for variations on a theme.
I have already sort of asked this question already here (Previous Question) but it only got a handful of views and zero answers/comments so I thought I'd give it a go again with some more info that I've found.
I basically have a Windows Store DirectX + XAML app that I'm developing. I currently have the problem that the Rendering event of the SwapChainBackgroundPanel that I use for DirectX rendering (as per the Windows 8 example on MSDN) sometimes isn't called when the user is interacting with the app.
It will continue to update if I am doing something with the camera such as changing what it's looking at based on touch/mouse position but it won't be called if I am picking and I don't know why.
I use the standard GPU picking method (where I render the scene with a unique color for each object and then take a 1x1 texture of the press area to find the selected object) but when I am using this picking technique to select multiple objects (the user drags their finger/mouse over many objects) Rendering isn't being called. So in effect what happens is, lots of objects get selected but the user only sees this when they remove their finger/stop pressing the mouse button.
Is there any reason why this is happening? Is it because of the GPU picking method? And if so is there a way around it rather than using the ray-trace picking method (which considerably slows down picking for a large number of objects)?
Has anyone else had this problem? Is there an explanation from Microsoft anywhere that it is deliberate that rendering doesn't get called while this is happening?
Thanks for your time.
I've created an in app email feature to ask a question that opens the mfmailcomposer and fills it with html content. Unfortunately it seems to cut off the final line of the email so it appears as the image below.
I have set the mfmailcomposer to self, followed every tutorial I can find, the only reference to fix it has said the following:
make sure your mfmailcomposer is set to self ie. [self presentModalViewController:email animated:YES];
make sure it's embedded within a navigation controller
Neither solution works.
I have found that if the email contents is short enough that the entire email fits on screen the problem doesn't appear but if you continue typing to push the contents off the edge it reappears.
Any ideas on a solution? Or is this an Apple xcode "design feature"?
I managed to resolve this issue, it seems to be a bug, that's the only explanation I can reach.
If the start of your content is a header (<h1>, <h2>, <h3>, etc) tag (even if it is within a HTML and BODY tag) it creates this issue.
If you want to start your email body with a header tag then the simplest way of fixing it is to add a non breaking spacer before the header tag, it seems to completely resolve the issue.
Possibly a framework bug. Does it occur on different versions of iOS? Try it with both older and newer versions of the operating system and on other devices.
Are you 100% certain that the view is not actually larger than its container view? Explore the view hierarchy. Perhaps in plaintext Apple adds some spacing, so it doesn't seem like the content is out of bounds of the parent view, although it is.
How do scroll indicators behave? Are they also clipped?
Are you presenting the message composer in a fullscreen view? If you're trying to present it in a view that is controlled by a sub-controller of the tab view controller, that might cause the composer view controller to be confused.
For what it's worth, I've just tested my code which generates HTML content, and there is no clipping. This is on iOS 4.2.1 on iPhone 3G, but I don't remember seeing the problem on iOS 5.1 either.
Some tips.
While debugging, don't forget: view controllers are actually just managing views that still have their own hierarchies. To clarify, view controllers may have a hierarchy, but their hierarchy does not necessarily correspond to view hierarchy. (Although it should in the near total majority of cases.) Same thing with views themselves: they have their hierarchy, but they still just control the underlying Core Animation layers, which have their own hierarchy.
You can always access view hierarchy itself and explore it in greater detail through debugging facilities you come up with yourself. What you shouldn't be doing is meddling too much in parts of the view hierarchy that's supposed to be managed by the view controllers, just like you shouldn't mess too much with the parts of the layer hierarchy that's supposed to be managed by the views.
I have a question regarding NSMenuItems.
What I'm trying to do is replicate a java GUI using native OS X components, therefore the language I am using is Cocoa. What I am trying to do is to get every menu item to have an image and then, beside it, some text.
I have already done some research into it and my first port of call (as always it seems lol) was the apple docs which had this handy example which illustrates how to embed views inside menuitems:
https://developer.apple.com/library/mac/#samplecode/MenuItemView/Listings/MyWindowController_m.html#//apple_ref/doc/uid/DTS10004136-MyWindowController_m-DontLinkElementID_8
Being relatively new to cocoa, I was thinking I would have to override one of the drawing methods from NSMenuItem. Not really sure though.
Another idea that I was toying with was creating a custom view that held a image and some text.
Any other ideas/validation or discussion would be most appreciated.
Thanks all!
Oh and the GUI creation is being done by hand no interface builder.
Okay, so I now have menu items with icons beside them. For anyone who is interested here it is ( i've not done a leak analysis on it or anything).
First things first, put all of the images you want into the "Resources" folder (thats what its called in xcode 3.1.4).
Now, for example, after we have all the images, we want to use images called "eraser.png" and "eraser_on.png" and I want to attach these to the 3rd menu item. In order to achieve this we do the following :
The code below will get the menu item at position 3 in the menu
NSMenuItem *item = [ nameOfPopUpButton itemAtIndex:2];
The code below will set the image for the menu item to be "eraser.png"
[ item setImage: [ NSImage imageNamed:#"eraser"] ];
That's you set the image for the menu item (which will be on the left hand side of the text aka before the text).
If you want different images for the different states, eg when the user presses it, use this method (not tested myself but its sounds sensible :D and the function is straight out the api)
[item setOnStateImage: [ NSImage imageNamed:#"eraser_on" ] ]
You can however leave it nil or not set it at all and it will go the default color
Hope this helps someone.
Pieced this together from: https://developer.apple.com/library/mac/#samplecode/MenuMadness/Listings/Controller_m.html#//apple_ref/doc/uid/DTS40008870-Controller_m-DontLinkElementID_4
Thanks :)
If you need to do this you have the right idea in creating a view with image and label subviews.
BUT: don't do this. Creating a "native" application is not primarily about your choice of language (which is Objective-C, btw, not Cocoa; the latter is a collection of development frameworks implemented in Objective-C). It's about conforming to the platform.
On OS X (and iOS), more than probably any other platform, consistency in UI design is paramount. Users know when an application looks strange, and having icons next to each menu item (something I certainly have seen in Java apps) is definitely strange and unnatural on OS X. Users will be irritated at best, confused at worst.
So my advice is to either follow the Human Interface Guidelines (and save yourself a lot of work as a nice side effect) or just stick with your existing Java application.
If you want to provide quick iconic access to common functions, the recommended approach on OS X is to use a toolbar.
I have a large data set (some 3500 objects) that returns from a remote server via HTTP. Currently the data is being presented in an NSCollectionView. One aspect of the data is a path pack to the server for a small image that represents the data (think thumbnail for simplicity).
Bindings works fantastically for the data that is already returned, and binding the image via a valueurl binding is easy to do. However, the user interface is very sluggish when scrolling through the data set - which makes me think that the NSCollectionView is retrieving all the image data instead of just the image data used to display the currently viewable images.
I was under the impression that Cocoa controls were smart enough to only retrieve data for the information that is actually being output to the user interface through lazy loading. This certainly seems to be the case with NSTableView - but I could be misguided on this thought.
Should valueurl binding act lazily and, moreover, should it act lazily in an NSCollectionView?
I could create a caching mechanism (in fact I already have such a thing in place for another application - see my post here if you are interested Populating NSImage with data from an asynchronous NSURLConnection) but I really don't want to go this route if I don't have to for this specific implementation as the user could potentially change data sets often and may only want small sub-sets of the data.
Any suggested approaches?
Thanks!
Update
After some more testing it seems that the problem arises because a scroll action through the data set causes each image to be requested from the server. Once all the images have been passed over in the data set the response is very fast.
So question... is there any way of turning off the valueurl fetch while scrolling and turning it back on when scrolling has finished?
My solution is to use a custom caching mechanism like the one I already use for another application. The problem manifests itself because as you scroll past images that have not yet been downloaded, the control triggers itself to go and fetch the as yet non-downloaded files.
Once downloaded the images are available locally and therefore scrolling speed normalizes. The solution is to check to see if the image is available locally and present an alternate app-bundle graphic while the image is being downloaded in the background. Once the image has been downloaded, update the model with the image replacing the stub image that came from the bundle.
This leaves the UI in a very responsive state throughout, leaves the user with the ability to interact and allows for a custom background management of the images.
Of course it would have been nice if Cocoa id all this for me, but then what would I be left to do? :-)