I have built iPhone game application which has loads of views. The next view gets decided based on the user's current action. It working fine absolutely. I want to start a timer when my game gets started and want to keep incrementing till game finished. Nothing fency! The problem is I can put label on view and use NS Timer ticks to increment its value but how to synchronize that value when move to next view?
Could anyone please let me know if there is already framwork available that support this or any way to implement this.
Thanks.
The easiest solution would be to have the timer be a property in your app delegate, so you can access it from any view/view controller. That's what I'd do here. It doesn't seem to "belong" to individual views based on what you've described.
Related
I'm working on a multiview app. One of the views is a table view. Each cell has a stopwatch. I'm planning to use NSTimer for the stopwatches. Do I need to implement multithreading for the timers to work properly even when the user switches the view and then comes back later?
I did my research but most of the tutorials cover one NSTimer in a single view. I want to make sure the user can do other things while the timers are running, like use the interface, navigation, etc. In another post Placing an NSTimer in a separate thread someone said you need a different runloop for the timer. Would I need one runloop for each timer in my case? Is it advisable? Any performance drawbacks?
Thanks a lot!
One run loop should be just fine. Your interface will still be responsive.
Keep in mind that timers are never guaranteed to be accurate. They are affected by how much other stuff is on the same loop. Its ok to use the timer to update the display but not to actually measure time. Set an NSDate when you start a stop watch then compare the current date with that start date each time your display timer updates the display.
Since you should only use the NSTimer to update the display, could you just use one generic display update timer that updates all running stopwatches, instead of having one for each stopwatch?
I have a TabBar Application with 2 tabs saving/fetching data to and from CoreData. The problem that I am having is that when the form has been filled and the user has touched the save button the view is not re-loaded or re-initialised. All I want is for the view to be ready for the user to repeat the process with the next set of information. I am probably not thinking about this in the correct way so a pointer in the right direction would be very much appreciated...
Do I need to manually set everything including the managedObjectContext etc. to nil? Or is there something that I can do with methods like viewWillDisappear that will elegantly help me to "re-initialise" that specific tab?
I ave read up the Apple docs on view hierarchies, and life cycles but I just seem to have confused myself...
Thanks in advance for any suggestions, referrals to code or even recommendations on relevant reading material.
It sounds like what you want to do is reload any data to their default states when the user taps a button. Unfortunately, you'll have to do this manually, setting each IBOutlet's value to a meaningful default (probably the empty string).
There are two ways I can think of that would help make this more elegant:
Use an IBOutletCollection and fast enumeration to loop over all the IBOutlets and not have a bunch of code to do each one individually.
If you're switching tabs in between these events, you can something neat and use your app delegate as your UITabBarControllerDelegate for the tabBarController:didSelectViewController: to call the clearing-out method for you instead of relying on viewDidAppear.
I am fairly new to Objective-C, but haven't been able to find the answer I am looking for yet.
I am building a practice app which counts down days till specific events (christmas). It all works well, but I wanted to implement a simple way to change the background image (created from storyboards). The current setup of the app is a basic utility app, with the alternate view containing a UISegmentedControl that will set which background image will be displayed behind the countdown label.
I know I can just push separate views, but that seems quite inefficient. I am fairly sure I can use NSNotifications to update the background image, but am still unclear after reading the documentation how to implement it.
One way is to use delegates. A delegate is a callback. That avoids one view passing a reference to another view and having it poke (introduces coupling). Instead, one provides a callback via a formal protocol and delegate to the other.
Here's an SO question that covers it:
What exactly does delegate do in xcode ios project?
Another option is to have a shared model. Using a singleton pattern, multiple views can share a model (data and operations) and you can use NSNotificationCenter to send notifications. When the other view gets the notification that the background changed, it can query the model and update the background.
Related posts:
Giving notification to another class with NSNotificationCenter
How to share an object with the entire project?
As far as the pros and cons go, basically a notification is good when you want to broadcast a change to multiple views. Delegation is good when two items need to communicate directly with some abstraction.
NSNotificationCenter vs delegation( using protocols )?
k, I'm new to this so apologies all around, generally.
I'm trying to access the UISwitch value (on or off) from a different view and class and can't make it work.
It's a simple 2 view app. Main view and the second is a preference menu.
trying to write an if/else method to play sound when the switch (on the other view) is on and not when its off.
I cant seem to make it work. Any thoughts or some syntax examples would really help me out.
Thanks.
As Matt Wilding said "it's not good form to access UI components of one view controller from another...".
Instead of accessing the view object, when the switch state is changed by the user you save the status into NSUserDefaults as preference value. Whenever you want, you can access the switch status value through the preferences.
I'm going to take what I think you're trying to accomplish here and suggest an alternative approach. You want to have a preference in your app (assumed from "preferences menu") that allows the user to set something like whether or not you app plays background music. (May not be exact, this is just for clarification).
Typically, in a well designed app, the flow is driven by the data, with the UI reflecting the state of the data model and the controllers coordinating the two layers. What you are suggesting is to have your application play music based on the state of the UI, which is not backed by any data model. This cuts out the model level, and as you noticed, can lead to awkward attempts at communicating between the UI of different controllers for information.
Things like application preferences are typically stored in a nifty .plist file that is managed through the NSUserDefaults class. This would be a great place for the data level tracking of your preference. In this situation, the UISwitch would represent the state of the flag in the settings file, and changing the value of the switch would change the value in the file. Anywhere else in your application that you need to know if the play-sound-flag is set, you reference the data model info instead of the UI. This decouples the view controllers from each other, which is a good thing.
For this purpose add selector for swith and make NSInteger property in app delegate.Like the followed
[
yourSwitch addTarget:self action:#selector(switched:) forControlEvents:UIControlEventValueChanged];
-(IBAction) switched: (id)sender
{
int state=0;
if(yourSwitch.on)
state=1;
else
state=0;
objAppDelegate.switchState=state;
}
then you need to access this appDelegate property in second view where you are playing sound
then according to this value you can do what you want and for making object of appDelegate class you need this line
YourAppDelegateClass *objAppDelegate=(YourAppDelegateClass *)[[UIApplication sharedApplication] delegate];
ok if you have any other doubt then you can ask.
Hey all, I'm completely stumped with this iPhone problem.
This is my first time building a view programmatically, without a nib. I can get the view displaying things just fine, but the darn ViewController isn't responding to touches the way it used to in programs where I used a nib. I should add that in the past, I started with the View-Based Application template, and this time I used the Window-Based Application template.
My thinking is that the View-Based template does something magical to let the iPhone know where to send the touch events, but I can't figure out what that would be even after several hours of bumbling around Google. Or I could be looking in an entirely wrong place and my troubles are related to something else entirely. Any thoughts?
There's nothing magical in the view-based template. The most likely reasons for failure to respond to touches are:
You've messed with touchesBegan:withEvent:, userInteractionEnabled, exclusiveTouch or something else, thinking you need to mess with these (generally you don't; the defaults are generally correct)
You created a second UIWindow
You put something over the view (even if it's transparent)
Simplify your code down to just creating a view programatically that responds to a touch and nothing else. It should be just a few lines of code. If you can't get that working, post the code and we'll look at what's going on.
Problem solved. touchesEnded != touchedEnded.
That'll teach me to program without my glasses on.
Another possible scenario for failure in response to touches is when your VC frame is not predefined and its boundaries are actually exceeding the window placeholder. It happens a lot when you just forget to define the frame property for the VC.
Once you define it correctly - User interaction returns to normal.
Good luck !