如何将CGPoint存储在数组中

Question

你好，我正在尝试将移动点存储在NSMutableArray中，所以我尝试了以下方法：

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *move = [[event allTouches] anyObject];
    CGPoint MovePoint = [move locationInView:self.view];
if (MovePointsArray==NULL) {
        MovePointsArray=[[NSMutableArray alloc]init];
    }
    [MovePointsArray arrayWithObjects:[NSValue valueWithCGPoint:MovePoint]];
}

但是这种方式不起作用，我应该如何将这些点存储在NSMutableArray中？

- Nik's

Answer 1

你应该在最后一行使用addObject：

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *move = [[event allTouches] anyObject];
    CGPoint MovePoint = [move locationInView:self.view];
if (MovePointsArray==NULL) {
        MovePointsArray=[[NSMutableArray alloc]init];
    }
    [MovePointsArray addObject:[NSValue valueWithCGPoint:MovePoint]];
}

- justadreamer

Answer 2

你应该这样做：

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *move = [[event allTouches] anyObject];
    CGPoint MovePoint = [move locationInView:self.view];

    if (MovePointsArray == NULL) {
        MovePointsArray = [[NSMutableArray arrayWithObjects:[NSValue valueWithCGPoint:MovePoint, nil];
    }
    else {
        [MovePointsArray addObject:[NSValue valueWithCGPoint:MovePoint]];
    }
}

不要忘记在不使用属性访问器时保留/释放数组。

最好在init方法中分配/初始化数组，然后仅在此处执行：

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *move = [[event allTouches] anyObject];
    CGPoint MovePoint = [move locationInView:self.view];

    [MovePointsArray addObject:[NSValue valueWithCGPoint:MovePoint]];
}

- Oliver

Answer 3

如果您想使用arrayWithObjects方法获取一个数组，您还必须将nil作为数组的最后一个元素添加进去。

就像这样：

[MovePointsArray arrayWithObjects:[NSValue valueWithCGPoint:MovePoint], nil];

但是如果要将一个对象添加到现有的数组中，您应该使用addObject方法。

[MovePointsArray addObject:[NSValue valueWithCGPoint:MovePoint]];

- Cyprian