add SKAction to Sprite queue run one after another - objective-c

Question

I listen to touch and add SKAction to a sprite. If existing actions are not complete yet, I want the action to be added to a queue so it will execute one after another.
Any experienced similar design?
I did using Array and Block. If there is any easier approach?
#interface GAPMyScene()
#property(strong,nonatomic)SKSpriteNode*ufo;
#property(strong,nonatomic)NSMutableArray*animationQueue;
#property(copy,nonatomic)void(^completeMove)();
#end
#implementation GAPMyScene
-(id)initWithSize:(CGSize)size {
if (self = [super initWithSize:size]) {
self.ufo = [SKSpriteNode spriteNodeWithImageNamed:#"Spaceship"];
self.animationQueue = [[NSMutableArray alloc] init];
__unsafe_unretained typeof(self) weakSelf = self;
self.completeMove = ^(void){
[weakSelf.ufo runAction:[SKAction sequence:[weakSelf.animationQueue copy]] completion:weakSelf.completeMove];
NSLog(#"removeing %#", weakSelf.animationQueue);
[weakSelf.animationQueue removeAllObjects];
};
[self addChild:self.ufo];
}
return self;
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
for (UITouch *touch in touches) {
CGPoint location = [touch locationInNode:self];
SKAction*moveAnimation = [SKAction moveTo:location duration:2];
if (![self.ufo hasActions]) {
[self.ufo runAction:moveAnimation completion:self.completeMove];
} else {
[self.animationQueue addObject:moveAnimation];
NSLog(#"in queue %#", self.animationQueue);
}
}
}
#end

Answer 1

Generally, you can make SKActions run concurrently using the group method, and have them run sequentially using the sequence method.
But if you need a queuing system, rather than building your own, use the native operation queue to do this for you. So you can create a serial operation queue and add operations to it. The issue is that you don't want an operation to complete until the SKAction does.
So, you can wrap your SKAction in a concurrent NSOperation subclass that only completes when the SKAction does. Then you can add your operations to a serial NSOperationQueue, and then it will won't start the next one until it finishes the prior one.
So, first, create an ActionOperation (subclassed from NSOperation) that looks like:
// ActionOperation.h
#import <Foundation/Foundation.h>
#class SKNode;
#class SKAction;
#interface ActionOperation : NSOperation
- (instancetype)initWithNode:(SKNode *)node action:(SKAction *)action;
#end
and
// ActionOperation.m
#import "ActionOperation.h"
#import SpriteKit;
#interface ActionOperation ()
#property (nonatomic, readwrite, getter = isFinished) BOOL finished;
#property (nonatomic, readwrite, getter = isExecuting) BOOL executing;
#property (nonatomic, strong) SKNode *node;
#property (nonatomic, strong) SKAction *action;
#end
#implementation ActionOperation
#synthesize finished = _finished;
#synthesize executing = _executing;
- (instancetype)initWithNode:(SKNode *)node action:(SKAction *)action
{
self = [super init];
if (self) {
_node = node;
_action = action;
}
return self;
}
- (void)start
{
if ([self isCancelled]) {
self.finished = YES;
return;
}
self.executing = YES;
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
[self.node runAction:self.action completion:^{
self.executing = NO;
self.finished = YES;
}];
}];
}
#pragma mark - NSOperation methods
- (BOOL)isConcurrent
{
return YES;
}
- (void)setExecuting:(BOOL)executing
{
[self willChangeValueForKey:#"isExecuting"];
_executing = executing;
[self didChangeValueForKey:#"isExecuting"];
}
- (void)setFinished:(BOOL)finished
{
[self willChangeValueForKey:#"isFinished"];
_finished = finished;
[self didChangeValueForKey:#"isFinished"];
}
#end
You could then, for example, create a serial queue during the initialization process:
self.queue = [[NSOperationQueue alloc] init];
self.queue.maxConcurrentOperationCount = 1;
You can then add the operations to it:
SKAction *move1 = [SKAction moveTo:point1 duration:2.0];
[self.queue addOperation:[[ActionOperation alloc] initWithNode:nodeToMove action:move1]];
and you can later add more actions:
SKAction *move2 = [SKAction moveTo:point2 duration:2.0];
[self.queue addOperation:[[ActionOperation alloc] initWithNode:nodeToMove action:move2]];
And because the queue is serial, you know that move2 will not be started until move1 is done.