Spritekit Subclassed節點顯示爲零

Question

Heyo夥計們，在嘗試在SpriteKit中創建子類節點時出現了一個奇怪的問題。我在編譯時沒有遇到任何錯誤，並且應用程序一直運行到節點需要添加爲場景的子節點，然後失敗並說reason: 'Attemped to add nil node to parent:我不確定我錯過了什麼，感謝任何幫助！下面是我的節點標題：

#import <SpriteKit/SpriteKit.h> 

@interface Ships : SKSpriteNode 

-(Ships *)initWithImageNamed: (NSString *)imageName; 

@end 

，這裏是實現：

#import "Ships.h" 

@implementation Ships 

-(Ships *)initWithImageNamed: (NSString *)imageName 
{ 
self = [Ships spriteNodeWithImageNamed:imageName]; 

// Adds more accurate physics body for ship collisions 
CGFloat offsetX = (self.frame.size.width * 1.2) * self.anchorPoint.x; 
CGFloat offsetY = (self.frame.size.height * 1.2) * self.anchorPoint.y; 

CGMutablePathRef path = CGPathCreateMutable(); 

CGPathMoveToPoint(path, NULL, 8 - offsetX, 30 - offsetY); 
CGPathAddLineToPoint(path, NULL, 7 - offsetX, 22 - offsetY); 
CGPathAddLineToPoint(path, NULL, 50 - offsetX, 2 - offsetY); 
CGPathAddLineToPoint(path, NULL, 65 - offsetX, 7 - offsetY); 
CGPathAddLineToPoint(path, NULL, 70 - offsetX, 8 - offsetY); 
CGPathAddLineToPoint(path, NULL, 27 - offsetX, 31 - offsetY); 

CGPathCloseSubpath(path); 

self.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:path]; 
self.physicsBody.dynamic = NO; 
self.physicsBody.restitution = 0.0f; 
self.physicsBody.friction = 0.0f; 
self.physicsBody.linearDamping = 1.0f; 
self.physicsBody.allowsRotation = NO; 
self.physicsBody.usesPreciseCollisionDetection = YES; 

// Keeps player ship on top of all other objects(unless other objects are assigned greater z position 
self.zPosition = 100.0f; 

return self; 
} 

@end 

在我的場景

然後，我在interface與申報playerNode：Ships *playerNode;，這裏是試圖實現節點的方法：

-(void) createPlayerNode 
{ 
playerNode = [playerNode initWithImageNamed:@"Nova-L1"]; 
playerNode.position = CGPointMake(self.frame.size.width/5, self.frame.size.height/2); 
playerNode.physicsBody.categoryBitMask = CollisionCategoryPlayer; 
playerNode.physicsBody.collisionBitMask = 0; 
playerNode.physicsBody.contactTestBitMask = CollisionCategoryBottom | CollisionCategoryObject | CollisionCategoryScore | CollisionCategoryPup; 

[self addChild:playerNode]; 
} 

我在應用程序的其他地方打電話[self createPlayerNode];，一旦我崩潰了。任何幫助是極大的讚賞！另外，我在我的iPhone 5

Answer 1

船舶的初始化運行是一個實例方法不是類的方法，所以你分配/初始化語句應該

playerNode = [[Ships alloc] initWithImageNamed:@"Nova-L1"]]; 

和Ships.m，更換

self = [Ships spriteNodeWithImageNamed:imageName]; 

與此

self = [super initWithImageNamed:imageName]; 

另外，你應該創建to後釋放路徑他物理體...

ship.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:path]; 

    CGPathRelease(path); 

或者，你可以在Ships.m中聲明一個方便的方法來在一個步驟中分配/ init。

編輯：在Ships.m

聲明類方法

+ (Ships *)shipNodeWithImageNamed:(NSString *)imageName 
{ 
    return [[Ships alloc] initWithImageNamed:imageName]; 
} 

Add方法原型Ships.h

+ (Ships *)shipNodeWithImageNamed:(NSString *)imageName; 

和

創建一個新的節點船

playerNode = [Ships shipNodeWithImageNamed:@"Nova-L1"];