gistfile1.txt

- (instancetype)initWithPoints:(NSArray *)points {
    NSParameterAssert(points);
    NSParameterAssert([points objectAtIndex:0]);
    NSParameterAssert([[points objectAtIndex:0] isKindOfClass:[NSValue class]]);
    
    self = [super init];
    
    if (self) {

        for (NSValue *value in points) {
            [self.points addObject:value];
        }
    }
    return self;
}

// super init:

- (instancetype)init {
    self = [super init];
    
    if (self) {
        self.lines = [NSMutableArray array];
        self.points = [NSMutableArray array];
    }
    
    return self;
}