Question

我有一个NSArray，我用SKTexture填充动物跳跃动画：

    @interface PSFrogNode ()

@property (strong, nonatomic) NSArray *leapFrames;

@end

@implementation PSFrogNode {

}

- (instancetype)init
{
    self = [super init];
    if (self) {

        SKTextureAtlas *frogLeapAtlas = [SKTextureAtlas atlasNamed:kFrogLeapAtlas];

        int numImages = frogLeapAtlas.textureNames.count;
        NSMutableArray *tempArray = [NSMutableArray arrayWithCapacity:numImages];
        for (int i=1; i <= numImages/2; i++) {
            NSString *textureName = [NSString stringWithFormat:@"frogLeap%d", i];
            SKTexture *temp = [frogLeapAtlas textureNamed:textureName];
            [tempArray addObject:temp];
        }
        self.leapFrames = [NSArray arrayWithArray:tempArray];
        self = [PSFrogNode spriteNodeWithTexture:[self.leapFrames objectAtIndex:0]];
        [self setUserInteractionEnabled:NO];
    }
    return self;
}

- (void)animateFrogLeap
{
    [self runAction:[SKAction animateWithTextures:self.leapFrames timePerFrame:0.09 resize:NO restore:YES]];
}

数组self.leapFrames在init方法中分配，但是当场景调用animateFrogLeap方法时，它是空的（意思是nil）。那是为什么？

Answer 1

您想在init方法之外创建数组，然后将其传递到：

创建视图时

SKTextureAtlas *frogLeapAtlas = [SKTextureAtlas atlasNamed:kFrogLeapAtlas];

int numImages = frogLeapAtlas.textureNames.count;
NSMutableArray *images = [NSMutableArray arrayWithCapacity:numImages];
for (int i=1; i <= numImages/2; i++) {
    NSString *textureName = [NSString stringWithFormat:@"frogLeap%d", i];
    SKTexture *temp = [frogLeapAtlas textureNamed:textureName];
    [images addObject:temp];
}

PSFrogNode *node = [[PSFrogNode alloc] initWithImages:images];
// Now use the node

<强> PSFrogNode.h

-(instancetype)initWithImages:(NSArray *)images;

<强> PSFrogNode.m

@interface PSFrogNode ()

@property (nonatomic, copy) NSArray *leapFrames;

@end

@implementation PSFrogNode 

-(instancetype)initWithImages:(NSArray *)images
{
    self = [self initWithTexture:[images firstObject]];
    if (self) {
        _leapFrames = [images copy];
        [self setUserInteractionEnabled:NO];
    }
    return self;
}

正如我的评论中所提到的，原始实现中的下一行将意味着self将被重新分配，因此它之前的行（将数组分配给属性）将意味着更少。

self = [PSFrogNode spriteNodeWithTexture:[self.leapFrames objectAtIndex:0]];

强烈保留数组为空

1 个答案: