我實現的解決方案確實使用隊列。這裏有一個非常完整的描述：
這一切都在一個名爲PlayerView的視圖類中完成。在報頭中我包括以下內容：
#import "NSMutableArray+QueueAdditions.h"
@interface PlayerView : UIImageView {
Player* representedPlayer; // The model object represented by the view
NSMutableArray* actionQueue; // An array used as a queue for the actions
bool animatingPlayer; // Notes if the player is in the middle of an animation
bool stoppingAnimation; // Notes if all animations should be stopped (e.g., for re-setting the game)
CGFloat actionDuration; // A convenient way for me to change the duration of all animations
// ... Removed other variables in the class (sound effects, etc) not needed for this example
}
// Notifications
+ (NSString*) AnimationsDidStopNotification;
@property (nonatomic, retain) Player* representedPlayer;
@property (nonatomic, retain, readonly) NSMutableArray* actionQueue;
@property (nonatomic, assign) CGFloat actionDuration;
@property (nonatomic, assign) bool animatingPlayer;
@property (nonatomic, assign) bool stoppingAnimation;
// ... Removed other properties in the class not need for this example
- (void)placePlayer; // puts view where needed (according to the model) without animation
- (void)moveEventHandler:(NSNotification *) notification; // handles events when the player moves
- (void)rotateEventHandler:(NSNotification *) notification; // handles events when the player rotates
// ... Removed other action-related event handles not needed for this example
// These methods actually perform the proper animations
- (void) doMoveAnimation:(CGRect) nextFrame;
- (void) doRotateAnimation:(CGRect)nextFrame inDirection:(enum RotateDirection)rotateDirection;
// ... Removed other action-related methods not needed for this example
// Handles things when each animation stops
- (void) animationDidStop:(NSString*)animationID
finished:(BOOL)finished
context:(void*)context;
// Forces all animations to stop
- (void) stopAnimation;
@end
順便說一句，在的NSMutableArray + QueueAdditions.h /米QueueAdditions類別看起來像這樣：
@interface NSMutableArray (QueueAdditions)
- (id)popObject;
- (void)pushObject:(id)obj;
@end
@implementation NSMutableArray (QueueAdditions)
- (id)popObject
{
// nil if [self count] == 0
id headObject = [self objectAtIndex:0];
if (headObject != nil) {
[[headObject retain] autorelease]; // so it isn't dealloc'ed on remove
[self removeObjectAtIndex:0];
}
return headObject;
}
- (void)pushObject:(id)obj
{
[self addObject: obj];
}
@end
接着，在PlayerView的實施，我有以下幾點：
#import "PlayerView.h"
#import <QuartzCore/QuartzCore.h>
@implementation PlayerView
@synthesize actionQueue;
@synthesize actionDuration;
@synthesize animatingPlayer;
@synthesize stoppingAnimation;
// ... Removed code not needed for this example (init to set up the view's image, sound effects, actionDuration, etc)
// Name the notification to send when animations stop
+ (NSString*) AnimationsDidStopNotification
{
return @"PlayerViewAnimationsDidStop";
}
// Getter for the representedPlayer property
- (Player*) representedPlayer
{
return representedPlayer;
}
// Setter for the representedPlayer property
- (void)setRepresentedPlayer:(Player *)repPlayer
{
if (representedPlayer != nil)
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
[representedPlayer release];
}
if (repPlayer == nil)
{
representedPlayer = nil;
// ... Removed other code not needed in this example
}
else
{
representedPlayer = [repPlayer retain];
if (self.actionQueue == nil)
{
actionQueue = [[NSMutableArray alloc] init];
}
[actionQueue removeAllObjects];
animatingPlayer = NO;
stoppingAnimation = NO;
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:@selector(moveEventHandler:)
name:[Player DidMoveNotification]
object:repPlayer ];
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:@selector(rotateEventHandler:)
name:[Player DidRotateNotification]
object:repPlayer ];
// ... Removed other addObserver actions and code not needed in this example
}
}
// ... Removed code not needed for this example
- (void) placePlayer
{
// Example not helped by specific code... just places the player where the model says it should go without animation
}
// Handle the event noting that the player moved
- (void) moveEventHandler: (NSNotification *) notification
{
// Did not provide the getRectForPlayer:onMazeView code--not needed for the example. But this
// determines where the player should be in the model when this notification is captured
CGRect nextFrame = [PlayerView getRectForPlayer:self.representedPlayer onMazeView:self.mazeView];
// If we are in the middle of an animation, put information for the next animation in a dictionary
// and add that dictionary to the action queue.
// If we're not in the middle of an animation, just do the animation
if (animatingPlayer)
{
NSDictionary* actionInfo = [NSDictionary dictionaryWithObjectsAndKeys:
[NSValue valueWithCGRect:nextFrame], @"nextFrame",
@"move", @"actionType",
@"player", @"actionTarget",
nil];
[actionQueue pushObject:actionInfo];
}
else
{
animatingPlayer = YES; // note that we are now doing an animation
[self doMoveAnimation:nextFrame];
}
}
// Handle the event noting that the player rotated
- (void) rotateEventHandler: (NSNotification *) notification
{
// User info in the notification notes the direction of the rotation in a RotateDirection enum
NSDictionary* userInfo = [notification userInfo];
NSNumber* rotateNumber = [userInfo valueForKey:@"rotateDirection"];
// Did not provide the getRectForPlayer:onMazeView code--not needed for the example. But this
// determines where the player should be in the model when this notification is captured
CGRect nextFrame = [PlayerView getRectForPlayer:self.representedPlayer onMazeView:self.mazeView];
if (animatingPlayer)
{
NSDictionary* actionInfo = [NSDictionary dictionaryWithObjectsAndKeys:
[NSValue valueWithCGRect:nextFrame], @"nextFrame",
@"rotate", @"actionType",
rotateNumber, @"rotateDirectionNumber",
@"player", @"actionTarget",
nil];
[actionQueue pushObject:actionInfo];
}
else
{
enum RotateDirection direction = (enum RotateDirection) [rotateNumber intValue];
animatingPlayer = YES;
[self doRotateAnimation:nextFrame inDirection:direction];
}
}
// ... Removed other action event handlers not needed for this example
// Perform the actual animation for the move action
- (void) doMoveAnimation:(CGRect) nextFrame
{
[UIView beginAnimations:@"Move" context:NULL];
[UIView setAnimationDuration:actionDuration];
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:context:)];
self.frame = nextFrame;
[UIView commitAnimations];
}
// Perform the actual animation for the rotate action
- (void) doRotateAnimation:(CGRect)nextFrame inDirection:(enum RotateDirection)rotateDirection
{
int iRot = +1;
if (rotateDirection == CounterClockwise)
{
iRot = -1;
}
[UIView beginAnimations:@"Rotate" context:NULL];
[UIView setAnimationDuration:(3*actionDuration)];
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:context:)];
CGAffineTransform oldTransform = self.transform;
CGAffineTransform transform = CGAffineTransformRotate(oldTransform,(iRot*M_PI/2.0));
self.transform = transform;
self.frame = nextFrame;
[UIView commitAnimations];
}
- (void) animationDidStop:(NSString*)animationID
finished:(BOOL)finished
context:(void *)context
{
// If we're stopping animations, clear the queue, put the player where it needs to go
// and reset stoppingAnimations to NO and note that the player is not animating
if (self.stoppingAnimation)
{
[actionQueue removeAllObjects];
[self placePlayer];
self.stoppingAnimation = NO;
self.animatingPlayer = NO;
}
else if ([actionQueue count] > 0) // there is an action in the queue, execute it
{
NSDictionary* actionInfo = (NSDictionary*)[actionQueue popObject];
NSString* actionTarget = (NSString*)[actionInfo valueForKey:@"actionTarget"];
NSString* actionType = (NSString*)[actionInfo valueForKey:@"actionType"];
// For actions to the player...
if ([actionTarget isEqualToString:@"player"])
{
NSValue* rectValue = (NSValue*)[actionInfo valueForKey:@"nextFrame"];
CGRect nextFrame = [rectValue CGRectValue];
if ([actionType isEqualToString:@"move"])
{
[self doMoveAnimation:nextFrame];
}
else if ([actionType isEqualToString:@"rotate"])
{
NSNumber* rotateNumber = (NSNumber*)[actionInfo valueForKey:@"rotateDirectionNumber"];
enum RotateDirection direction = (enum RotateDirection) [rotateNumber intValue];
[self doRotateAnimation:nextFrame inDirection:direction];
}
// ... Removed code not needed for this example
}
else if ([actionTarget isEqualToString:@"cell"])
{
// ... Removed code not needed for this example
}
}
else // no more actions in the queue, mark the animation as done
{
animatingPlayer = NO;
[[NSNotificationCenter defaultCenter]
postNotificationName:[PlayerView AnimationsDidStopNotification]
object:self
userInfo:[NSDictionary dictionaryWithObjectsAndKeys: nil]];
}
}
// Make animations stop after current animation by setting stopAnimation = YES
- (void) stopAnimation
{
if (self.animatingPlayer)
{
self.stoppingAnimation = YES;
}
}
- (void)dealloc {
if (representedPlayer != nil)
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
[representedPlayer release];
[actionQueue release];
// …Removed other code not needed for example
[super dealloc];
}
@end
說明：
視角子從模型對象（玩家）抄寫適當的通知。當捕獲通知時，它會檢查它是否已經在做動畫（使用animatingPlayer屬性）。如果是這樣，它會從通知中獲取信息（注意播放器應該如何動畫），將該信息放入字典中，然後將該字典添加到動畫隊列中。如果當前沒有動畫，該方法會將animatingPlayer設置爲true並調用適當的do [Whatever]動畫例程。
每個[無論]動畫例程執行適當的動畫，將setAnimationDidStopSelector設置爲animationDidStop：finished：context :.當每個動畫完成時，animationDidStop：finished：context：方法（在檢查是否應立即停止所有動畫之後）將執行隊列中的下一個動畫，方法是將下一個字典拖出隊列並解釋其數據以調用適當做[隨時]動畫方法。如果隊列中沒有動畫，則該例程將animatingPlayer設置爲NO併發布通知，以便其他對象可以知道播放器何時適當地停止了其當前動畫的運行。
就是這樣。可能有一個更簡單的方法（？），但這對我來說工作得很好。如果您有興趣查看實際結果，請查看我在App Store中的Mazin應用。
謝謝。