如何将CGPoint存储在数组中答案

【问题标题】：how to store CGPoint in array如何将CGPoint存储在数组中
【发布时间】：2011-10-07 14:09:47
【问题描述】：

嗨，我正在尝试将移动点存储在 NSMutableArray 中，所以我有这样的尝试

-(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]];
}

但这不起作用如何将这些点存储在NSMutableArray

【问题讨论】：

标签： iphone objective-c xcode cocoa-touch

【解决方案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]];
}

【讨论】：

【解决方案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]];
    }
}

不要忘记保留/释放数组，因为您看不到使用属性访问器。

最好，您应该在 init 方法中分配/初始化数组，然后只在此处执行：

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

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

【讨论】：

【解决方案3】：

如果要使用方法arrayWithObjects 获取数组，还必须添加nil 作为数组的最后一个元素。

像这样：

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

但是要将对象添加到现有数组中，您应该使用addObject 方法

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

【讨论】：