我正在制作一个游戏，目的是捕获从屏幕顶部掉落的多个对象。在底部有一个篮子来抓东西。我设法使用raywenderlich的教程从顶部到底部随机生成对象：http ://www.raywenderlich.com/42699/spritekit-tutorial-for-beginners
但是我想要的是，当我点击该随机对象时，该对象的图像会更改为另一幅图像，所以如果想像一下，如果随机对象是猫，则在我点击它们之后必须将它们变成狗，我该怎么做？编程这个？
编辑 这是我到目前为止所得到的：
#import "MyScene.h"
static NSString* basketCategoryName = @"basket";
static NSString* monsterCategoryName= @"monster";
static const uint32_t projectileCategory = 0x1 << 0;
static const uint32_t monsterCategory = 0x1 << 1;
@interface MyScene() <SKPhysicsContactDelegate>
@property (nonatomic) SKLabelNode * scoreLabelNode;
@property int score;
@property (nonatomic) SKSpriteNode * basket;
@property (nonatomic) SKSpriteNode * monster;
@property (nonatomic) BOOL isFingerOnBasket;
@property (nonatomic) BOOL isFingerOnMonster;
@property (nonatomic) BOOL isTouching;
@property (nonatomic) NSTimeInterval lastSpawnTimeInterval;
@property (nonatomic) NSTimeInterval lastUpdateTimeInterval;
//@property (nonatomic, strong) SKSpriteNode *selectedNode;
@end
@implementation MyScene
-(id)initWithSize:(CGSize)size {
if (self = [super initWithSize:size]) {
// Initialize label and create a label which holds the score
_score = 0;
_scoreLabelNode = [SKLabelNode labelNodeWithFontNamed:@"MarkerFelt-Wide"];
_scoreLabelNode.position = CGPointMake( CGRectGetMidX( self.frame ), 3 * self.frame.size.height / 4 );
_scoreLabelNode.zPosition = 100;
_scoreLabelNode.text = [NSString stringWithFormat:@"%d", _score];
[self addChild:_scoreLabelNode];
// Set the background
SKTexture* groundTexture = [SKTexture textureWithImageNamed:@"AcornFlipTestBackground1136x640.png"];
groundTexture.filteringMode = SKTextureFilteringNearest;
for( int i = 0; i < 2 + self.frame.size.width / ( groundTexture.size.width * 2 ); ++i ) {
SKSpriteNode* sprite = [SKSpriteNode spriteNodeWithTexture:groundTexture];
[sprite setScale:1.0];
sprite.size = CGSizeMake(self.frame.size.width,self.frame.size.height);
sprite.position = CGPointMake(CGRectGetMidX(self.frame),
CGRectGetMidY(self.frame));
[self addChild:sprite];
}
// Make grafity for sprite
self.physicsWorld.gravity = CGVectorMake(0.0f, 0.0f);
self.physicsWorld.contactDelegate = self;
// Make catching object sprite
self.basket = [SKSpriteNode spriteNodeWithImageNamed:@"bedTest.png"];
self.basket.position = CGPointMake(CGRectGetMidX(self.frame), _basket.frame.size.height * 0.5f);
self.basket.name = basketCategoryName;
[self addChild:self.basket];
// For default this is set to no until user touches the basket and the game begins.
self.isTouching = NO;
}
return self;
}
-(void)addAcorn{
if(_isTouching == YES) {
self.monster= [SKSpriteNode spriteNodeWithImageNamed:@"AcornFinal.png"];
// Determine where to spawn the monster along the X axis
int minX = self.monster.size.width;
int maxX = self.frame.size.width - self.monster.size.width;
int rangeX = maxX - minX;
int actualX = (arc4random() % rangeX)+minX;
// Random position along the X axis as calculated above
// This describe from which way the acorns move
// - means moving from top to the right and + means moving from the top to the left
self.monster.position = CGPointMake(actualX ,self.frame.size.height+ self.monster.size.height);
self.monster.name = monsterCategoryName;
[self addChild:self.monster];
CGSize contactSize = CGSizeMake(self.monster.size.width - 5.0, self.monster.size.height - 10.0);
self.monster.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:contactSize]; // 1
self.monster.physicsBody.dynamic = YES; // 2
self.monster.physicsBody.categoryBitMask = monsterCategory; // 3
self.monster.physicsBody.contactTestBitMask = projectileCategory; // 4
self.monster.physicsBody.collisionBitMask = 0; // 5
// Determine speed of the monster
int minDuration = 8.0;
int maxDuration = 10.0;
int rangeDuration = maxDuration - minDuration;
int actualDuration = (arc4random() % rangeDuration) + minDuration;
// Create the actions
SKAction * actionMove = [SKAction moveTo:CGPointMake(actualX,-self.monster.size.height) duration:actualDuration];
SKAction * actionMoveDone = [SKAction removeFromParent];
[self.monster runAction:[SKAction sequence:@[actionMove, actionMoveDone]]];
}
}
- (void)updateWithTimeSinceLastUpdate:(CFTimeInterval)timeSinceLast {
self.lastSpawnTimeInterval += timeSinceLast;
if (self.lastSpawnTimeInterval > 0.5) {
self.lastSpawnTimeInterval = 0;
[self addAcorn];
}
}
- (void)update:(NSTimeInterval)currentTime {
// Handle time delta.
// If we drop below 60fps, we still want everything to move the same distance.
CFTimeInterval timeSinceLast = currentTime - self.lastUpdateTimeInterval;
self.lastUpdateTimeInterval = currentTime;
if (timeSinceLast > 1) { // more than a second since last update
timeSinceLast = 1.0 / 60.0;
self.lastUpdateTimeInterval = currentTime;
}
[self updateWithTimeSinceLastUpdate:timeSinceLast];
}
-(void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
self.isTouching = YES;
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInNode:self];
SKNode* body = [self nodeAtPoint:location];
if ([body.name isEqualToString:basketCategoryName])
{
NSLog(@"Began touch on basket");
self.isFingerOnBasket = YES;
}
else if ([body.name isEqualToString:monsterCategoryName])
{
NSLog(@"Began touch on MONSTER");
self.isFingerOnMonster = YES;
}
}
-(void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event {
if (self.isFingerOnMonster) {
// 2 Get touch location
UITouch* touch = [touches anyObject];
CGPoint location = [touch locationInNode:self];
CGPoint previousLocation = [touch previousLocationInNode:self];
// 3 Get node for paddle
SKSpriteNode* monster = (SKSpriteNode*)[self childNodeWithName: monsterCategoryName];
int oldPosition = monster.position.x + (location.x - previousLocation.x);
self.monster = [SKSpriteNode spriteNodeWithImageNamed:@"AcornFinal.png"];
monster.position = CGPointMake(oldPosition, monster.position.y);
NSLog(@"reached the touch though");
}
// 1 Check whether user tapped paddle
if (self.isFingerOnBasket) {
// 2 Get touch location
UITouch* touch = [touches anyObject];
CGPoint location = [touch locationInNode:self];
CGPoint previousLocation = [touch previousLocationInNode:self];
// 3 Get node for paddle
SKSpriteNode* basket = (SKSpriteNode*)[self childNodeWithName: basketCategoryName];
// 4 Calculate new position along x for paddle
int basketX = basket.position.x + (location.x - previousLocation.x);
// 5 Limit x so that the paddle will not leave the screen to left or right
basketX = MAX(basketX, basket.size.width/2);
basketX = MIN(basketX, self.size.width - basket.size.width/2);
// 6 Update position of paddle
basket.position = CGPointMake(basketX, basket.position.y);
CGSize contactSize = CGSizeMake(basket.size.width - 8.0, basket.size.height - 8.0);
basket.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:contactSize];
basket.physicsBody.dynamic = YES;
basket.physicsBody.categoryBitMask = projectileCategory;
basket.physicsBody.contactTestBitMask = monsterCategory;
basket.physicsBody.collisionBitMask = 0;
basket.physicsBody.usesPreciseCollisionDetection = YES;
}
}
- (void)projectile:(SKSpriteNode *)basket didCollideWithMonster:(SKSpriteNode *)monster {
NSLog(@"Hit");
[monster removeFromParent];
}
- (void)didBeginContact:(SKPhysicsContact *)contact
{
// 1
SKPhysicsBody *firstBody, *secondBody;
if (contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask)
{
firstBody = contact.bodyA;
secondBody = contact.bodyB;
}
else
{
firstBody = contact.bodyB;
secondBody = contact.bodyA;
}
// 2
if ((firstBody.categoryBitMask & projectileCategory) != 0 &&
(secondBody.categoryBitMask & monsterCategory) != 0)
{
[self projectile:(SKSpriteNode *) firstBody.node didCollideWithMonster:(SKSpriteNode *) secondBody.node];
NSLog(@"test");
_score++;
_scoreLabelNode.text = [NSString stringWithFormat:@"%d", _score];
}
}
// Removing this void will result in being able to drag the basket accross the screen without touching the basket itself.
-(void)touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event {
self.isFingerOnBasket = NO;
self.isFingerOnMonster = NO;
}
@end
一旦在Sprite上检测到触摸（我假设您已经解决了问题），您可以使用再次创建Sprite spriteNodeWithImageNamed。确保保存前一个节点的位置，然后再次将其设置在新的精灵上，以使其与旧精灵的位置匹配。
CGPoint oldPosition = touchedSprite.position;
touchedSprite = [SKSpritNode spriteWithImageNamed:@"imgge.png"];
touchedSprite.position = oldPosition;
// If you have any other sprite properties you will have to save them as well
您也可以使用setTexture不需要其他任何更改（例如位置）的方法来设置纹理：
[touchedSprite setTexture:[SKTexture textureWithImageNamed:@"image.png"]];
编辑：在注释中回答您的问题，您可以在touchesEnded子对象的父节点的方法中实现此目标：
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
CGPoint touchLocation = [touch locationInNode:self];
for (SKSpriteNode *sprite in fallingSprites) { // Assuming fallingSprite is an array containing the cat sprites you want to detect touches for
if (CGRectContainsPoint(sprite.frame, touchLocation)) {
[sprite setTexture:[SKTexture textureWithImageNamed:@"dog.png"]];
}
}
}
另一种方法（尚未尝试过）是将SKSpriteNode子类化并实现相同的方法，但是在rect中没有触摸检测，因为如果此方法称为sprite，则已经被触摸。
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