SpriteKit很奇怪’PKPhysicsBody’崩溃
我正在尝试为SKPhysicsBody实现一个简单的类别，这将允许我将“完美弹跳”应用于物理主体。
这将简单地做的是当perfectBouncing = YES ，将发生以下情况：
restitution = 1.0
linearDamping = 0.0
friction = 0.0
但是，当我尝试使用如下所示的实现时，我得到一个奇怪的崩溃告诉我，我无法向perfectBouncing发送perfectBouncing消息， PKPhysicsBody是一个我从未引用过的类，在我的项目中不存在或者我在SpriteKit SDK中的知识。
是的，这个类别正在import。
崩溃消息
-[PKPhysicsBody setPerfectBouncing:]: unrecognized selector sent to instance 0x7fa828f84610 *** First throw call stack: ( 0 CoreFoundation 0x000000010882b3f5 __exceptionPreprocess + 165 1 libobjc.A.dylib 0x0000000107dbfbb7 objc_exception_throw + 45 2 CoreFoundation 0x000000010883250d -[NSObject(NSObject) doesNotRecognizeSelector:] + 205 3 CoreFoundation 0x000000010878a7fc ___forwarding___ + 988 4 CoreFoundation 0x000000010878a398 _CF_forwarding_prep_0 + 120 5 Squash The Dot 0x000000010785662c -[gameNode viewDidAnimateIn] + 1116 6 Squash The Dot 0x000000010783e709 -[lzyViewHandler initViewChild:] + 3305 7 Squash The Dot 0x000000010783d93d -[lzyViewHandler initViewChildren:] + 573 8 Squash The Dot 0x000000010785d3e0 __28-[splashVC viewDidAnimateIn]_block_invoke + 256 9 SpriteKit 0x000000010933837e _ZN9SKCAction25didFinishWithTargetAtTimeEP9SKCSprited + 44 10 SpriteKit 0x0000000109399638 _ZN9SKCSprite6updateEd + 170 11 SpriteKit 0x0000000109352dd4 -[SKScene _update:] + 119 12 SpriteKit 0x000000010936d299 -[SKView(Private) _update:] + 563 13 SpriteKit 0x000000010936ac2f -[SKView renderCallback:] + 829 14 SpriteKit 0x0000000109367cec __29-[SKView setUpRenderCallback]_block_invoke + 54 15 SpriteKit 0x0000000109394744 -[SKDisplayLink _callbackForNextFrame:] + 256 16 QuartzCore 0x00000001091f88f7 _ZN2CA7Display15DisplayLinkItem8dispatchEv + 37 17 QuartzCore 0x00000001091f87bf _ZN2CA7Display11DisplayLink14dispatch_itemsEyyy + 315 18 CoreFoundation 0x00000001087934e4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20 19 CoreFoundation 0x00000001087930a5 __CFRunLoopDoTimer + 1045 20 CoreFoundation 0x00000001087563dd __CFRunLoopRun + 1901 21 CoreFoundation 0x0000000108755a06 CFRunLoopRunSpecific + 470 22 GraphicsServices 0x000000010be319f0 GSEventRunModal + 161 23 UIKit 0x000000010953f550 UIApplicationMain + 1282 24 Squash The Dot 0x00000001078550a3 main + 115 25 libdyld.dylib 0x000000010b6cb145 start + 1 )
类别实施
#import @interface SKPhysicsBody (lzySKPhysics) // Enables perfect boucing by setting friction = 0, linearDamping = 0 and restitution = 1. @property (nonatomic) BOOL perfectBouncing; @end @implementation SKPhysicsBody (lzySKPhysics) -(BOOL) perfectBouncing { return (self.restitution == 1 && self.linearDamping == 0 && self.friction == 0); } -(void) setPerfectBouncing:(BOOL)perfectBouncing { self.restitution = perfectBouncing; self.linearDamping = !perfectBouncing; self.friction = !perfectBouncing; } @end
用法示例
hero = [[SKSpriteNode alloc] initWithColor:[SKColor blueColor] size:CGSizeMake(heroRadius*2, heroRadius*2)]; hero.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:heroRadius]; hero.physicsBody.perfectBouncing = YES;
任何想法，这个难以捉摸的PKPhysicsBody是什么，为什么我有这个崩溃？
在内部，Sprite Kit具有许多公共类的自定义类。 在这种情况下，SKPhysicsBody实际上创建了内部类PKPhysicsBody的实例。 推测PK代表“物理套件”。
这就是为什么你的类别不起作用的原因，如果我记得正确的施法也不会成功，因为SKPhysicsBody不会从PKPhysicsBodyinheritance，但如果我错了你可以这样试试：
((SKPhysicsBody)hero.physicsBody).perfectBouncing = YES;
无论如何，这里不需要类别。 相反，您可以使用辅助类和类方法实现相同的效果，例如：
@implementation SKPhysicsHelper +(BOOL) perfectBouncingWithBody:(SKPhysicsBody*)body { return (body.restitution == 1 && body.linearDamping == 0 && body.friction == 0); } +(void) setPerfectBouncing:(BOOL)perfectBouncing body:(SKPhysicsBody*)body { body.restitution = perfectBouncing; body.linearDamping = !perfectBouncing; body.friction = !perfectBouncing; } @end