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使用过渡场景在多个场景的切换COCOS2D(4)

2013-07-24 20:54 387 查看
CCNode有三个方法，使用CCDirector的replaceScene方法替换场景时，每个节点都会调用这三个方法：

onEnter与onExit方法在改变场景过程中的特定时刻被调用，这取决于是否使用CCTransitionScene。

onEnterTransitionDidFinish方法在替换结束时调用。

必须总是调用这些方法的超类实现来避免难输入问题和内存泄漏。

01
-(
void
) onEnter
02
{
03
CCLOG(@
"%@:%@"
, NSStringFromSelector(_cmd), self);
04
 
05
// must call super here:
06
[super onEnter];
07
}
08
 
09
-(
void
) onEnterTransitionDidFinish
10
{
11
CCLOG(@
"%@:%@"
, NSStringFromSelector(_cmd), self);
12
 
13
// must call super here:
14
[super onEnterTransitionDidFinish];
15
}
16
 
17
-(
void
) onExit
18
{
19
CCLOG(@
"%@:%@"
, NSStringFromSelector(_cmd), self);
20
 
21
// must call super here:
22
[super onExit];
23
}
编写过渡场景：

LoadingScene充当一个中间场景的角色，它是cocos2d中的CCScene类的派生类，不必为每一次场景创建一个新的LoadingScene。

代码清单：LoadingScene.h

01
#import <Foundation/Foundation.h>
02
#import "cocos2d.h"
03
 
04
typedef
 
enum
 
05
{
06
TargetSceneINVALID = 0,
07
TargetSceneFirstScene,
08
TargetSceneOtherScene,
09
TargetSceneMAX,
10
}TargetScenes;
11
 
12
<a href=
"http://my.oschina.net/interface"
 
class
=
"referer"
 
target=
"_blank"
>@interface</a>LoadingScene :CCScene {
13
 
14
TargetScenes targetScene_;
15
}
16
 
17
+(id) sceneWithTargetScene:(TargetScenes)targetScene;
18
-(id) initWithTargetScene:(TargetScenes)targetScene;
19
 
20
<a href=
"http://my.oschina.net/u/567204"
 
class
=
"referer"
 
target=
"_blank"
>@end</a>
使用enum给各个场景编个号，而且将enum的第一个值设为0,在Objective－c中变量的值会自动初始化为0.并在最后设了个MAX值。

代码清单：LoadingScene.m

01
#import "LoadingScene.h"
02
#import "MyFirstScene.h"
03
#import "OtherScene.h"
04
 
05
<a href=
"http://my.oschina.net/interface"
 
class
=
"referer"
 
target=
"_blank"
>@interface</a>LoadingScene (PrivateMethods) 
06
-(
void
) update:(ccTime)delta;
07
<a href=
"http://my.oschina.net/u/567204"
 
class
=
"referer"
 
target=
"_blank"
>@end</a>
08
 
09
@implementation LoadingScene
10
+(id) sceneWithTargetScene:(TargetScenes)targetScene;
11
{
12
CCLOG(@
"==========================================="
);
13
CCLOG(@
"%@:%@"
, NSStringFromSelector(_cmd), self);
14
 
15
// This creates an autorelease object of self (the current class:LoadingScene)
16
return
 
[[[self alloc] initWithTargetScene:targetScene] autorelease];
17
 
18
// Note:this does the exact same, it only replaced self with LoadingScene. The above is much more common.
19
//return [[[LoadingScene alloc] initWithTargetScene:targetScene] autorelease];
20
}
21
 
22
-(id) initWithTargetScene:(TargetScenes)targetScene
23
{
24
if
 
((self = [super init]))
25
{
26
targetScene_ = targetScene;
27
 
28
CCLabelTTF* label = [CCLabelTTF labelWithString:@
"Loading ..."
 
fontName:@
"Marker Felt"
 
fontSize:64];
29
CGSize size = [[CCDirector sharedDirector] winSize];
30
label.position = CGPointMake(size.width / 2, size.height / 2);
31
[self addChild:label];
32
 
33
// Must wait one frame before loading the target scene!
34
// Two reasons:first, it would crash if not. Second, the Loading label wouldn't be displayed.
35
[self scheduleUpdate];
36
}
37
 
38
return
 
self;
39
}
40
 
41
-(
void
) update:(ccTime)delta
42
{
43
// It's not strictly necessary, as we're changing the scene anyway. But just to be safe.
44
[self unscheduleAllSelectors];
45
 
46
// Decide which scene to load based on the TargetScenes enum.
47
// You could also use TargetScene to load the same with using a variety of transitions.
48
switch
 
(targetScene_)
49
{
50
case
 
TargetSceneFirstScene:
51
[[CCDirector sharedDirector] replaceScene:[MyFirstScene scene]];
52
break
;
53
case
 
TargetSceneOtherScene:
54
[[CCDirector sharedDirector] replaceScene:[OtherScene scene]];
55
break
;
56
 
57
default
:
58
// Always warn if an unspecified enum value was used. It's a reminder for yourself to update the switch
59
// whenever you add more enum values.
60
NSAssert2(nil, @
"%@:unsupported TargetScene %i"
, NSStringFromSelector(_cmd), targetScene_);
61
break
;
62
}
63
 
64
// Tip:example usage of the INVALID and MAX enum values to iterate over all enum values 
65
for
 
(TargetScenes i = TargetSceneINVALID + 1;i <TargetSceneMAX;i++) 
66
{
67
}
68
}
69
 
70
-(
void
) dealloc
71
{
72
CCLOG(@
"%@:%@"
, NSStringFromSelector(_cmd), self);
73
 
74
// don't forget to call "super dealloc"
75
[super dealloc];
76
}
77
<a href=
"http://my.oschina.net/u/567204"
 
class
=
"referer"
 
target=
"_blank"
>@end</a>
由于LoadingScene类由CCScene派生出来，所以不需要调用［CCScene node］，sceneWithTargetScene方法先为self分配空间，然后调用initWithTargetScene初始化。

在MyFirstScene中调用LoadingScene：

1
CCScene *newScene = [LoadingScene sceneWithTargetScene:TargetSceneOtherScene];
2
[[CCDirector sharedDirector] replaceScene:newScene];
在OtherScene中调用基本类似，请读者自行实践。

下面给出了在执行过程中的一些输出信息，它详细的说明了各个方法的调用顺序：

view source

print
?

01
2012-10-06 13:50:03.404 MutiScene[1884:1be03] ===========================================
02
2012-10-06 13:50:03.405 MutiScene[1884:1be03] scene:MyFirstScene 
03
2012-10-06 13:50:03.406 MutiScene[1884:1be03] init :<MyFirstScene = 0x94e2540 | Tag = -1>
04
2012-10-06 13:50:08.610 MutiScene[1884:1be03] cocos2d:animation started with frame interval:60.00 
05
2012-10-06 13:50:08.613 MutiScene[1884:1be03] cocos2d:surface size:480x320 
06
2012-10-06 13:50:08.614 MutiScene[1884:1be03] onEnter:<MyFirstScene = 0x94e2540 | Tag = -1>
07
2012-10-06 13:50:08.615 MutiScene[1884:1be03] onEnterTransitionDidFinish:<MyFirstScene = 0x94e2540 | Tag = -1>
08
2012-10-06 13:50:11.844 MutiScene[1884:1be03] ===========================================
09
2012-10-06 13:50:11.845 MutiScene[1884:1be03] scene:OtherScene 
10
2012-10-06 13:50:11.846 MutiScene[1884:1be03] init:<OtherScene = 0x9418280 | Tag = -1>
11
2012-10-06 13:50:16.907 MutiScene[1884:1be03] onEnter:<OtherScene = 0x9418280 | Tag = -1>
12
2012-10-06 13:50:19.944 MutiScene[1884:1be03] onExit:<MyFirstScene = 0x94e2540 | Tag = -1>
13
2012-10-06 13:50:19.945 MutiScene[1884:1be03] onEnterTransitionDidFinish:<OtherScene = 0x9418280 | Tag = -1>
14
2012-10-06 13:50:19.947 MutiScene[1884:1be03] dealloc :<MyFirstScene = 0x94e2540 | Tag = -1>
15
2012-10-06 13:50:29.953 MutiScene[1884:1be03] ===========================================
16
2012-10-06 13:50:29.954 MutiScene[1884:1be03] sceneWithTargetScene::LoadingScene 
17
2012-10-06 13:50:29.961 MutiScene[1884:1be03] onExit:<OtherScene = 0x9418280 | Tag = -1>
18
2012-10-06 13:50:29.962 MutiScene[1884:1be03] dealloc:<OtherScene = 0x9418280 | Tag = -1>
19
2012-10-06 13:50:29.977 MutiScene[1884:1be03] ===========================================
20
2012-10-06 13:50:29.979 MutiScene[1884:1be03] scene:MyFirstScene 
21
2012-10-06 13:50:29.980 MutiScene[1884:1be03] init :<MyFirstScene = 0x9418280 | Tag = -1>
22
2012-10-06 13:50:35.031 MutiScene[1884:1be03] dealloc:<LoadingScene = 0x11a59950 | Tag = -1>
23
2012-10-06 13:50:35.032 MutiScene[1884:1be03] onEnter:<MyFirstScene = 0x9418280 | Tag = -1>
24
2012-10-06 13:50:35.032 MutiScene[1884:1be03] onEnterTransitionDidFinish:<MyFirstScene = 0x9418280 | Tag = -1>

                                            

                                        

                        
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