How can I check if a method is or isn't running, in an if statement? For example-
if ([(UIButton *)sender isEqual:blueButton] && **showBlueText method is running** )
{
Keep playing.
}
else if ([(UIButton *)sender isEqual:blueButton] && **showBlueText method is NOT running** )
{
Game over.
}
-(void)showBlueText
{
blueText.hidden = NO;
[self performSelector:#selector(hideText) withObject:nil afterDelay:textDelay];
[self performSelector:#selector(showGreenText) withObject:nil afterDelay:hideDelay];
}
Just to clarify, 'showBlueText' is a part of its own loop that runs independently of this if statement. I'm just trying to check if showBlueText is currently running.
You want to record state here. Make a new instance variable in this class.
// new iVar
BOOL textIsShowing;
// method
-(void)showBlueText {
textIsShowing = YES;
blueText.hidden = NO;
[self performSelector:#selector(hideText) withObject:nil afterDelay:textDelay];
}
// method
- (void)hideText {
textIsShowing = NO;
blueText.hidden = YES;
}
// button press
- (void)buttonPressed {
if (textIsShowing) {
NSLog(#"Keep playing");
} else {
NSLog(#"Game over");
}
}
Between the time you call this method, and the animation stops, don't think of it as "running". It schedules code to be executed later. Instead you want to be notified after it has finally run.
And in this case it's easiest to keep track of the state yourself. Use a new variable to track the state of things, and change it's value when that state changes.
But can't you just check if (blueText.hidden)? Yeah, you could. But it's bad practice to store state about your program in some obscure property of a random unimportant object.
Examine your state to figure out what you show. Don't examine what's showing to figure out your state.
I suggest replace Keep playing or Game over or Doing stuff with NSLog() statements. I always use it to keep a track of the changes in program if I am getting unexpected result.
So your statement may look like:
NSLog(#"Keep playing");
I hope this helps.
Just check if the text is hidden. No need to store parallel state in your controller - all that does is create the possibility that they'll be out of sync.
Related
I have an algorithm that takes a few seconds to load some stuff, and I want to first set the string on a label to say "loading" before the actual loading begins. This is all within the same layer, this is not switching between scenes.
I thought I could simply do this:
-(void)startLoading{
[self unscheduleAllSelectors];//just in case the update is already scheduled
[self.loadingLabel setString:#"Loading...."];
[self scheduleUpdate];
}
Then, I have this:
-(void)update:(ccTime)delta{
[self unscheduleUpdate];
[self beginLoading];//another method that loads all the stuff
}
My understanding is that my method beginLoading should not run until the next frame. Thus my label should get updated correctly. However this is not happening. There is a slight freeze while all my assets get loaded and my label never gets updated before the loading begins.
Am I missing a step?
Nope ure not missing anything. I stopped fighting this and now use this kind of 'delayed' task catapult. It should make certain you will get a draw in the transition from the first to the second tick:
-(void) startLoading{
_loadTicker=0; // an NSUInteger iVar declared in the .h
[self schedule:#selector(tickOffLoading:)];
}
-(void) tickOffLoading:(ccTime) dt{
_loadTicker++;
if(_loadTicker==1) {
[self.loadingLabel setString:#"Loading...."];
} else {
[self unschedule:#selector(tickOffLoading:)];
[self beginLoading];
}
}
I have seen many tutorials over internet to detect blow in iPhone but my app's requirement is that I need to detect single blow and double blow both so that if user blow single time it can perform action a and if the user blow two times together then to perform action b.
Any way to do this?
Thanks all,
Surely if you know how to detect a single blow, you could just have a timer with a threshold & see if another blow happens within that time? Something like -
-(void)userDidBlow {
if (hasBlownOnce) {
hasBlownOnce = NO;
[NSObject cancelPreviousPerformRequestsWithTarget:self selector:#selector(singleBlowTimedOut) object:nil];
// do double-blow stuff
} else {
hasBlownOnce = YES;
[self performSelector:#selector(singleBlowTimedOut) withObject:nil afterDelay:kDoubleBlowTime];
}
}
-(void)singleBlowTimedOut {
hasBlownOnce = NO;
// do single-blow stuff
}
I haven't tested it, but it looks ok :)
My application is a VOIP telephony toolbox.
I have a series of UISwitch controls, which the user can use to change their settings, for example if they want to alter their caller id settings.
When the user changes the setting I need to make a call to the Telephony platform over its Restful API. If the Restful call fails, then I would like to reset the switch back to its previous setting. eg If the user turns caller ID on, and it fails because of a connection failure, I would like the switch to revert back to off.
I implemented this in my switchChangedValue method, however it creates a nasty loop. When a failure happens I set the UISwitch to its previous setting, but it in turn calls the switchChangedValue method again, which fails and so on looping
Here is part of my switchChangedValue method, any ideas welcome.
//Check if its a valid response from the XSI server
if ([bs getHTTPResponseCode] >= 200 && [bs getHTTPResponseCode] < 300) {
//This is the successful case
}
else
{
// I throw an alert here
//Id really like to change the UISwitch back if it goes wrong but it causes a bad loop.
if (buttonstate == false){
[switchbutton setOn:YES animated:YES];
//This invokes my switchChangedValue again
}
else if (buttonstate == true){
[switchbutton setOn:NO animated:YES];
//This invokes my switchChangedValue again
} else{
NSLog(#"Something went bad");
}
[bs release];
You might try something like this:
Declare this in your header:
BOOL _fireAPICall;
Set it to YES whenever the particular class you're in is initialized:
- (id)init {
if (self = [super init]) {
...
_fireAPICall = YES;
...
}
return self;
}
Then:
if (_fireAPICall) {
if ([bs getHTTPResponseCode] >= 200 && [bs getHTTPResponseCode] < 300) {
// success
} else {
// failure
_fireAPICall = NO;
[switchbutton setOn:!buttonstate animated:YES];
}
} else {
_fireAPICall = YES;
// handle case where switch is turned off if necessary
}
This is assuming that you're not making an API call when the user manually turns the switch off, though - is that the case?
Updated above!
I have a loading screen that I initialise with a label to display the loading progression.
I want to call my DataManager AFTER initialising the loading screen, and then call a method to switch scenes. Here is my code:
-(id) init {
if((self=[super init]))
{
loadingLabel = ....
[self addChild:loadingLabel];
/***** This is what I want to call after the init method
//DataManager loads everything needed for the level, and has a reference to the
//loading screen so it can update the label
[[DataManager sharedDataManager] loadLevel:#"level1" screen:self];
//this will switch the scene
[self finishLoading];
*****/
}
return self;
}
-(void) setLoadingPercentage:(int) perc {
//changes the label
}
-(void) finishLoading {
[[CCDirector sharedDirector] replaceScene:[Game node]];
}
So I can't call the datamanager in the init, because the label will not get updated as content gets loaded, and I can't switch scenes in the init method. So How do I run my datamanger and finish loading AFTER the init? My plan was to set a schedule at an interval of 1 second that does this, but it doesn't seem right to have to wait a second.
EDIT: another way I could do it is to schedule at every frame and ask the datamanager where its at... This seems better already, since the datamanager wouldn't need a reference to the loading screen.
Any ideas?
You can use performSelector:withObject:afterDelay: to force the execution of the specified selector during the next iteration of the current threads run loop:
[self performSelector:#selector(finishLoading) withObject:nil afterDelay:0.0f];
The above answer is correct, but you should use the Cocos2d way to schedule methods to run later:
[self schedule:#selector(finishLoading) interval:0.1];
-(void)finishLoading
{
[self unschedule:#selector(finishLoading)];
//Do your stuff
}
I am able to download a ZIP file from the internet. Post processing is done in connectionDidFinishLoading and works OK except no UIView elements are updated. For example, I set statusUpdate.text = #"Uncompressing file" but that change does not appear until after connectionDidFinishLoading has completed. Similarly, the UIProgressView and UIActivityIndicatorView objects are not updated until this method ends.
Is there any way to force an update of the UIView from within this method? I tried setting [self.view setNeedsDisplay] but that didn't work. It appears to be running in the main thread. All other commands here work just fine - the only problem is updating the UI.
Thanks!
Update: here is the code that is NOT updating the UIVIEW:
-(void)viewWillAppear:(BOOL)animated {
timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(processUpdate:) userInfo:nil repeats:YES];
downloadComplete = NO;
statusText.text = #"";
}
-(void)processUpdate:(NSTimer *)theTimer {
if (! downloadComplete) {
return;
}
[timer invalidate];
statusText.text = #"Processing update file.";
progress.progress = 0.0;
totalFiles = [newFiles count];
for (id fileName in newFiles) {
count++;
progress.progress = (float)count / (float)totalFiles;
// ... process code goes here ...
}
}
At then end of processUpdate, I set downloadComplete = YES. This builds & runs without errors and works as intended except nothing updates in the UIVIEW until after processUpdate completes, then everything updates at once.
Thanks for your help so far!
As Niels said, you must return control to the run loop if you want to see views update. But don't start detaching new threads unless you really need to. I recommend this approach:
- (void)connectionDidFinishLoading:(NSConnection *)connection {
statusUpdate.text = #"Uncompressing file";
[self performSelector:#selector(doUncompress) withObject:nil afterDelay:0];
}
- (void)doUncompress {
// Do work in 100 ms chunks
BOOL isFinished = NO;
NSDate *breakTime = [NSDate dateWithTimeIntervalSinceNow:100];
while (!isFinished && [breakTime timeIntervalSinceNow] > 0) {
// do some work
}
if (! isFinished) {
statusUpdate.text = // here you could update with % complete
// better yet, update a progress bar
[self performSelector:#selector(doUncompress) withObject:nil afterDelay:0];
} else {
statusUpdate.text = #"Done!";
// clean up
}
}
The basic idea is that you do work in small chunks. You return from your method to allow the run loop to execute periodically. The calls to performSelector: will ensure that control eventually comes back to your object.
Note that a risk of doing this is that a user could press a button or interact with the UI in some way that you might not expect. It may be helpful to call UIApplication's beginIgnoringInteractionEvents to ignore input while you're working... unless you want to be really nice and offer a cancel button that sets a flag that you check in your doUncompress method...
You could also try running the run loop yourself, calling [[NSRunLoop currentRunLoop] runUntilDate:...] every so often, but I've never tried that in my own code.
While you are in connectionDidFinishLoading nothing else happens in the application run loop. Control needs to be passed back to the run loop so it can orchestrate the UI updating.
Just flag the data transfer as complete and the views for updating. Defer any heavy processing of the downloaded data to it's own thread.
The application will call your views back letting them refresh their contents later in the run loop. Implement drawRect on your own custom views as appropriate.
If you're receiving connectionDidFinishLoading in the main thread, you're out of luck. Unless you return from this method, nothing will be refreshed in the UI.
On the other hand, if you run the connection in a separate thread, then you can safely update the UI using the following code:
UIProgressView *prog = ... <your progress view reference> ...
[prog performSelectorOnMainThread:#selector(setProgress:)
withObject:[NSNumber numberWithFloat:0.5f]
waitUntilDone:NO];
Be careful not to update the UI from a non-main thread - always use the performSelectorOnMainThread method!
Do exactly what you're doing with the timer, just dispatch your processing code to a new thread with ConnectionDidFinish:. Timers can update the UI since they're run from the main thread.
The problem turned out to that the UI isn't updated in a for() loop. See the answer in this thread for a simple solution!