Is possible stop a loop into a method call by selector?
I have created a new method for stop all running process, but I don't know how stop while loop in the audioloop method.
This is my code, please see:
-(id) init{
if((self=[super init]) ) {
// #property int isLoop;
self.isLoop = 1;
audioThread = [NSThread new];
[audioThread initWithTarget:self selector:#selector(audioLoop) object:nil];
[audioThread setThreadPriority:1];
[audioThread start];
}
}
// in this method i would stop while loop of audioLoop method
-(void)stopAllRunning{
self.isLoop = 0;
[audioThread cancel];
}
-(void) audioLoop{
while (isLoop) {
[_midiClock update];
}
}
Just add a condition and a break statement for doing this:
while (true)
{
if(yourCondition)
break;
else
[_midiClock update];
}
or Simply:
while (yourCondition)
{
[_midiClock update];
}
Related
I have two independent delegate methods in a class.
- (void)delegateMethod1:(id)data {
self.data = data;
}
- (void)delegateMethod2 {
[someClass sendData:self.data];
}
Now, this works fine sometimes but the other times, delegateMethod2 gets called before delegateMethod1.
I need to know how to manage this elegantly so that the line: [someClass sendData:self.data]; gets called only when both delegateMethod1 and delegateMethod2 have been called.
I know I can do it by using a variable to set to something on each delegate call but there has to be an elegant way to do this.
Any help?
Remembering which delegate has been called seems the easiest and cleanest solution to me.
But you can make it symmetric by moving the check to a separate method, so that
is does not matter which delegate is called first:
- (void)checkIfDataCanBeSent {
if (self.method1called && self.method2called) {
[someClass sendData:self.data];
}
}
- (void)delegateMethod1:(id)data {
self.method1called = YES;
// ...
[self checkIfDataCanBeSent];
}
- (void)delegateMethod2 {
self.method2called = YES;
// ...
[self checkIfDataCanBeSent];
}
(I have assumed that all delegate methods are called on the main thread, otherwise
one would have to add some synchronization.)
I believe, using a indicative variable to be the most elegant way to get over this. But this variable has to be kept in the delegate caller object.
Pseudo-type explanation
#interface DelegateCaller
{
BOOL hasCalled1stMethod;
}
#property(nonatomic,weak) id delegate;
#end
#implementation DelegateCaller
-(void)in_some_process_1
{
[self.delegate delegateMethod1]; //call
hasCalled1stMethod = YES; //set indicator
}
-(void)in_some_process_2
{
if(hasCalled1stMethod)
{
[self.delegate delegateMethod2]; //call
hasCalled1stMethod = NO; //reset indicator for reuse, if required.
}
}
#end
This way you'll not have to maintain any variable in the delegate itself, because the regulation of calling is maintained in the caller-object itself.
Another case:
If the delegateMethod1 is called from some object1 and the delegateMethod2 is called from some other object2, then again the indicative variable method is the most elegant way (in this limited scenario)
Pseudo-type explanation:
#interface ClassDelegateObject //aka the callee
{
BOOL hasCalledMethod1;
}
#end
#implementation ClassDelegateObject
-(void)delegateMethod1:(NSData*)data
{
self.data = data;
hasCalledMethod1 = YES; //set the indicator.
}
-(void)delegateMethod2
{
//here relying on the self.data!=nil will not be fruitful
//in case the self.data is not nil and hold some previous garbage data then
//this logic will fail.
if(hasCalledMethod1)
{
[someClass sendData:self.data];
hasCalledMethod1 = NO; //reset the variable for reuse if required.
}
}
#end
I would suggest that you rethink how the code works. Maybe you can check if there is no data and if so send it once it is ready:
- (void)delegateMethod1:(id)data {
self.data = data;
if (self.dataShouldBeSentWhenReady) {
[self sendData];
}
}
- (void)delegateMethod2 {
if (self.data) {
[self sendData];
} else {
[self setDataShouldBeSentWhenReady:YES];
}
}
- (void)sendData {
[self setDataShouldBeSentWhenReady:NO];
[someClass sendData:self.data];
}
Scenario:
User taps a button asking for some kind of modification on address book.
A method is called to start this modification and an alert view is shown.
In order to show the alert view and keep the UI responsive, I used dispatch_queue:
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
dispatch_sync(dispatch_get_main_queue(), ^{
// Show the alert view
});
});
Start the process of address book modification using:
dispatch_async(modifyingAddressBookQueue, ^{});
Now, I want to provide the user with the ability to cancel the process anytime (of course before saving the address book). So when he taps the cancel button in the alert sheet, I want to access the dispatch block, set some certain BOOL to stop the process and revert the address book.
The problem is, you can't do that! you can't access the block and change any variable inside it since all variables are copied only once. Any change of variables inside the block while being executed won't be seen by the block.
To sum up: How to stop a going operation using a UI event?
Update:
The code for the process:
- (void) startFixingModification {
_fixContacts = YES;
__block BOOL cancelled = NO;
dispatch_queue_t modifyingAddressBookQueue;
modifyingAddressBookQueue = dispatch_queue_create(sModifyingAddressBookQueueIdentifier,
NULL);
dispatch_async(modifyingAddressBookQueue, ^{
for (NSMutableDictionary *contactDictionary in _contactArray) {
if (!cancelled) {
break;
}
i = i + 1;
BOOL didFixContact = [self fixNumberInContactDictionary:contactDictionary];
if (!didFixContact) {
_fixedNumbers = _fixedNumbers - 1;
}
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
dispatch_sync(dispatch_get_main_queue(), ^{
[self setAlertViewProgress:i];
});
});
}
});
cancelledPtr = &cancelled;
}
Code for alertview (my own lib) delegate
- (void) alertViewProgressCancel:(ASAlertViewProgress *)alertView { // This is a private lib.
if (cancelledPtr)
{
NSLog(#"stopping");
*cancelledPtr = YES;
}
}
In interface, I declare
BOOL* cancelledPtr;
Update 2:
It's getting really frustrating! for the following code
for (NSMutableDictionary *contactDictionary in _contactArray) {
NSLog(#"%d", _cancelModification);
if (_cancelModification) {
break;
}
}
if _cancelModification is set to YES, the for loop is broken and that's OK. Once I comment out the NSLog line, the _cancelModification is neglected when it changes to YES!
If you declare your BOOL using __block, then it can be changed outside of the block execution, and the block will see the new value. See the documentation for more details.
An example:
#interface SNViewController ()
{
BOOL* cancelledPtr;
}
#end
#implementation SNViewController
- (IBAction)start:(id)sender
{
__block BOOL cancelled = NO;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
while (!cancelled) {
NSLog(#"running");
sleep(1);
}
NSLog(#"stopped");
});
cancelledPtr = &cancelled;
}
- (IBAction)stop:(id)sender
{
if (cancelledPtr)
{
NSLog(#"stopping");
*cancelledPtr = YES;
}
}
#end
Alternatively, use an ivar in your class to store the BOOL. The block will implicitly make a copy of self and will access the ivar via that. No need for __block.
#interface SNViewController ()
{
BOOL cancelled;
}
#end
#implementation SNViewController
- (IBAction)start:(id)sender
{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
while (!cancelled) {
NSLog(#"running");
sleep(1);
}
NSLog(#"stopped");
});
}
- (IBAction)stop:(id)sender
{
NSLog(#"stopping");
cancelled = YES;
}
#end
Approach 1
Create a custom dispatch_async method that returns a "cancelable" block.
// The dispatch_cancel_block_t takes as parameter the "cancel" directive to suspend the block execution or not whenever the block to execute is dispatched.
// The return value is a boolean indicating if the block has already been executed or not.
typedef BOOL (^dispatch_cancel_block_t)(BOOL cancelBlock);
dispatch_cancel_block_t dispatch_async_with_cancel_block(dispatch_queue_t queue, void (^block)())
{
__block BOOL execute = YES;
__block BOOL executed = NO;
dispatch_cancel_block_t cancelBlock = ^BOOL (BOOL cancelled) {
execute = !cancelled;
return executed == NO;
};
dispatch_async(queue, ^{
if (execute)
block();
executed = YES;
});
return cancelBlock;
}
- (void)testCancelableBlock
{
dispatch_cancel_block_t cancelBlock = dispatch_async_with_cancel_block(dispatch_get_main_queue(), ^{
NSLog(#"Block 1 executed");
});
// Canceling the block execution
BOOL success1 = cancelBlock(YES);
NSLog(#"Block is cancelled successfully: %#", success1?#"YES":#"NO");
// Resuming the block execution
// BOOL success2 = cancelBlock(NO);
// NSLog(#"Block is resumed successfully: %#", success2?#"YES":#"NO");
}
Approach 2
Defining a macro for executing a block asynchronously if a condition is validated:
#define dispatch_async_if(queue,condition,block) \
dispatch_async(queue, ^{\
if (condition == YES)\
block();\
});
- (void)testConditionBlock
{
// Creating condition variable
__block BOOL condition = YES;
dispatch_async_if(dispatch_get_main_queue(), condition, ^{
NSLog(#"Block 2 executed");
});
// Canceling the block execution
condition = NO;
// Also, we could use a method to test the condition status
dispatch_async_if(dispatch_get_main_queue(), ![self mustCancelBlockExecution], ^{
NSLog(#"Block 3 executed");
});
}
Try to apply the following code sample to your situation:
__block UIView * tempView = [[UIView alloc] initWithFrame:CGRectMake(50, 100, 220, 30)];
[tempView setBackgroundColor:[UIColor grayColor]];
[self.view addSubview:tempView];
[tempView release];
__block BOOL cancel = NO;
//点击之后就会开始执行这个方法
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(queue, ^{
int i = 0;
while (i < 1000000000 && cancel == NO) {
i++;
}
NSLog(#"Task end: i = %d", i);
//这个不会执行，因为在之前，gcd task已经结束
[tempView removeFromSuperview];
});
//1s 之后执行这个方法
double delayInSeconds = 1.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
NSLog(#"A GCD Task Start");
cancel = YES;
[tempView setBackgroundColor:[UIColor blackColor]];
});
Everything looks fine, I have no errors, yet, when I run the program it crashes. Please help, I'm getting frustrated. Here's what I have:
-(id) init {
if( (self=[super init])) {
homeCloud1 = [CCSprite spriteWithFile:#"homeCloud1.png"];
homeCloud1.position = ccp(140,200);
[self addChild:homeCloud1];
[self schedule:#selector(callEveryFrame)];
}
return self;
}
-(void) callEveryFrame: (ccTime) dt {
homeCloud1.position = ccp(homeCloud1.position.x +20*dt, homeCloud1.position.y);
if (homeCloud1.position.x > 480+30) {
homeCloud1.position = ccp(-30, homeCloud1.position.y);
}
}
Cant say for sure, post your crash log but there is one error I see
[self schedule:#selector(callEveryFrame)];
needs a colon
[self schedule:#selector(callEveryFrame:)];
I have my NSTimer embedded in a class that plays image sequences. Basically it loops and changes a UIImageView. Everything goes well if I let the image sequence finish but... on it's own if I try to stop the timer while it is playing I get a sigabrt. Edit: No longer a sigabrt but now a DeAlloc I can't explain.
The "stop" at the end of a frame sequence is the same stop I am calling mid sequence.
So what might cause an NSTimer to break mid function and DeAlloc. More to the point what might I look at to fix it.
Thanks.
I am using some example code from here: http://www.modejong.com/iOS/PNGAnimatorDemo.zip
Edit: I'll add what I believe to be the pertinent code here.
// Invoke this method to start the animation
- (void) startAnimating
{
self.animationTimer = [NSTimer timerWithTimeInterval: animationFrameDuration target: self selector: #selector(animationTimerCallback:) userInfo: NULL repeats: TRUE];
[[NSRunLoop currentRunLoop] addTimer: animationTimer forMode: NSDefaultRunLoopMode];
animationStep = 0;
if (avAudioPlayer != nil)
[avAudioPlayer play];
// Send notification to object(s) that regestered interest in a start action
[[NSNotificationCenter defaultCenter]
postNotificationName:ImageAnimatorDidStartNotification
object:self];
}
- (void) animationTimerCallback: (NSTimer *)timer {
if (![self isAnimating])
return;
NSTimeInterval currentTime;
NSUInteger frameNow;
if (avAudioPlayer == nil) {
self.animationStep += 1;
// currentTime = animationStep * animationFrameDuration;
frameNow = animationStep;
} else {
currentTime = avAudioPlayer.currentTime;
frameNow = (NSInteger) (currentTime / animationFrameDuration);
}
// Limit the range of frameNow to [0, SIZE-1]
if (frameNow < 0) {
frameNow = 0;
} else if (frameNow >= animationNumFrames) {
frameNow = animationNumFrames - 1;
}
[self animationShowFrame: frameNow];
// animationStep = frameNow + 1;
if (animationStep >= animationNumFrames) {
[self stopAnimating];
// Continue to loop animation until loop counter reaches 0
if (animationRepeatCount > 0) {
self.animationRepeatCount = animationRepeatCount - 1;
[self startAnimating];
}
}
}
- (void) stopAnimating
{
if (![self isAnimating])
return;
[animationTimer invalidate];
self.animationTimer = nil;
animationStep = animationNumFrames - 1;
[self animationShowFrame: animationStep];
if (avAudioPlayer != nil) {
[avAudioPlayer stop];
avAudioPlayer.currentTime = 0.0;
self->lastReportedTime = 0.0;
}
// Send notification to object(s) that regestered interest in a stop action
[[NSNotificationCenter defaultCenter]
postNotificationName:ImageAnimatorDidStopNotification
object:self];
}
Edit2: So I commented out an NSAssert in DeAlloc, commenting that out shed a bit more light. Now getting to self.animationTimer = nil; and saying *** -ImageAnimator setAnimationTimer:]: Message sent to deallocated instance.
DeAlloc is being called right when I invalidate the timer... so I'm a bit confused here.
I have a solution which is working but not optimal.
I just added another function to set the frame it's on to the last frame and it ends the sequence as I need.
But it doesn't solve the question of why it's doing it's crashing if I try to stop the sequence mid run.
Well, I wrote this code so I can assure you that it should be working just fine :) You need to invoke stopAnimating before you are done with the view, the only way you would have got the assert in dealloc is if the view was deallocated while it was still animating. That should not happen, which is exactly why there way an assert there. There is also a big comment explaining the assert, what is unclear about that?
- (void)dealloc {
// This object can't be deallocated while animating, this could
// only happen if user code incorrectly dropped the last ref.
NSAssert([self isAnimating] == FALSE, #"dealloc while still animating");
self.animationURLs = nil;
self.imageView = nil;
self.animationData = nil;
self.animationTimer = nil;
[super dealloc];
}
Just call:
[view stopAnimating];
Before you remove the view from its superview and everything will be just fine.
Please, I need help in making this code work. I intend to do an animation with a sprite I added using cocos2d and box2d in xcode. But for some odd reasons I cannot get the sprite to animate repeatedly.
This code builds successfully but animates only once. Can anyone help and tell me what I am not doing right?
The implementation file are as follows:
#import "Mosquito.h"
#import "Box2DHelpers.h"
#implementation Mosquito
#synthesize flyingAnim;
- (void) dealloc{
[flyingAnim release];
[super dealloc];
}
-(void)initAnimations {
flyingAnim = [self loadPlistForAnimationWithName:#"flyingAnim"
andClassName:NSStringFromClass([self class])];
[[CCAnimationCache sharedAnimationCache] addAnimation:flyingAnim
name:#"flyingAnim"];
}
-(void)changeState:(CharacterStates)newState {
[self stopAllActions];
id action = nil;
// id flyingAction = nil;
//CGPoint newPosition;
[self setCharacterState:newState];
switch (newState) {
case kStateIdle:
[self setDisplayFrame:
[[CCSpriteFrameCache sharedSpriteFrameCache]
spriteFrameByName:#"Mosquito_anim_1.png"]];
break;
case kStateFlying:
action = [CCAnimate actionWithAnimation:flyingAnim
restoreOriginalFrame:NO];
break;
case kStateTakingDamage:
action = [CCBlink actionWithDuration:1.0 blinks:3.0];
break;
default:
//CCLOG(#"Unhandled state %d in Mosquito", newState);
break;
}
if (action != nil) {
[self runAction:action];
}
}
- (id)initWithWorld:(b2World *)theWorld atLocation:(CGPoint)location {
if ((self = [super init])) {
world = theWorld;
[self setDisplayFrame:[[CCSpriteFrameCache
sharedSpriteFrameCache]
spriteFrameByName:#"Mosquito_anim_1.png"]];
gameObjectType = kMosquitoType;
characterHealth = 100.0f;
[self createBodyAtLocation:location];
[self initAnimations];
}
return self;
}
- (void) updateStateWithDeltaTime:(ccTime)deltaTime
andListOfGameObjects:(CCArray *)listOfGameObjects {
//CGPoint oldPosition = self.position;
if ((characterState == kStateDestroyed) &&
([self numberOfRunningActions] > 0)) {
return;
}
if (characterState != kStateFlying &&
[self numberOfRunningActions] == 0) {
[self changeState:kStateFlying];
}
}
#end
Thanks.
id repeatAnimation = [CCRepeatForever actionWithAction:action];
To repeat forever, you need to do that, otherwise you need to just do:
[self runAction:action];
again.
Also, you might want to consider not reassigning action to CCBlink and make another action and call
[self stopAllActions];
id blinkAction = [CCBlink actionWithDuration:1.0 blinks:3.0];
[self runAction:blinkAction];
This may Help you.
One of the easiest ways for sprite animation.
https://sites.google.com/site/rajanallathambi1/cocos2d-tutorials/sprite-animation-without-plist-file