iOS 子类化 SKShapeNode

Question

如何对没有实例方法初始化器的 SKShapeNode 进行子类化？我能想到的唯一方法是:

+ (id)withColor:(UIColor *)aColor radius:(CGFloat)aRadius {
    return [[self alloc] initWithColor:aColor radius: aRadius];
}

- (id)initWithColor:(UIColor *)aColor radius:(CGFloat)aRadius {
    self = (CAButtonNode *)[SKShapeNode shapeNodeWithCircleOfRadius:aRadius];
    self.fillColor = aColor;
    self.strokeColor = [UIColor clearColor];

    return self;
}

在这种情况下，self 是 SKShapeNode 而不是 CAButtonNode 的实例。

谢谢。

Answer 1

您可以向 SKShapeNode 添加类扩展

extension SKShapeNode
{
    class func nodeWithColor( color:UIColor, radius:Float ) -> Self
    {
        let node = SKShapeNode()
        node.path = CGPathCreateWithEllipseInRect(...)
        node.fillColor = ...
        node.strokeColor = ...

        return node
    }
}

像这样使用:

let newNode = SKShapeNode.nodeWithColor( <i>theColor</i>, radius: <i>theRadius</i> )

或者，在 Obj-C 中:

@implementation SKShapeNode (NodeWithColorAndRadius)

+(instancetype)nodeWithColor:(UIColor*)color radius:(CGFloat)r
{
    SKShapeNode * result = [ self new ] ;
    result.path = ...;
    result.fillColor = ...;
    result.strokeColor = ...;
}

@end

这样调用:

[ SKShapeNode nodeWithColor:<i>theColor</i> radius:<i>theRadius</i> ]