如何将类id的对象强制转换为CGPoint for NSMutableArray？

Question

如果我有一个类id的对象myObject,我将如何将其"转换"为CGPoint(假设我已经执行了内省并且知道myObject到CGPoint)？尽管CGPoint不是真正的Obj-C类.

只需执行(CGPoint)myObject返回以下错误:

Used type 'CGPoint' (aka 'struct CGPoint') where arithmetic or pointer type is required

我想这样做,以便我可以检查传递给NSMutableArray的对象是否是CGPoint,如果是,则自动将CGPoint包装在NSValue中; 例如:

- (void)addObjectToNewMutableArray:(id)object
{
    NSMutableArray *myArray = [[NSMutableArray alloc] init];
    id objectToAdd = object;
    if ([object isKindOfClass:[CGPoint class]]) // pseudo-code, doesn't work
    {
        objectToAdd = [NSValue valueWithCGPoint:object];
    }
    [myArray addObject:objectToAdd];
    return myArray;
}

附加代码

以下是我用来执行"内省"的功能:

+ (BOOL)validateObject:(id)object
{
    if (object)
    {
        if ([object isKindOfClass:[NSValue class]])
        {
            NSValue *value = (NSValue *)object;
            if (CGPointEqualToPoint([value CGPointValue], [value CGPointValue]))
            {
                return YES;
            }
            else
            {
                NSLog(@"[TEST] Invalid object: object is not CGPoint");
                return NO;
            }
        }
        else
        {
            NSLog(@"[TEST] Invalid object: class not allowed (%@)", [object class]);
            return NO;
        }
    }
    return YES;
}

+ (BOOL)validateArray:(NSArray *)array
{
    for (id object in array)
    {
        if (object)
        {
            if ([object isKindOfClass:[NSValue class]])
            {
                NSValue *value = (NSValue *)object;
                if (!(CGPointEqualToPoint([value CGPointValue], [value CGPointValue])))
                {
                    NSLog(@"[TEST] Invalid object: object is not CGPoint");
                    return NO;
                }
            }
            else
            {
                NSLog(@"[TEST] Invalid object: class not allowed (%@)", [object class]);
                return NO;
            }
        }
    }
    return YES;
}

+ (NSValue *)convertObject:(CGPoint)object
{
    return [NSValue valueWithCGPoint:object];
}

Answer 1

A CGPoint不是Objective-C对象.你不能将一个传递给你的addObjectToNewMutableArray:方法.编译器不会让你.

您需要包装CGPointin NSValue并将该包装器传递给您的addObjectToNewMutableArray:方法.

如果您有,NSValue并且您想测试它是否包含a CGPoint,您可以这样问:

if (strcmp([value objCType], @encode(CGPoint)) == 0) {
    CGPoint point = [value CGPointValue];
    ...
}