Question

我想在视图中的特定字段中跳球，问题是我不知道如何定义这个领域和运动的位置。也这是我用来在整个视图中移动球的代码（球对象是视图上的uiimageview）。感谢。

- （void）onTimer { ball.center = CGPointMake（ball.center.x + pos.x，ball.center.y + pos.y）;

if(ball.center.x > 320 || ball.center.x < 0)
    pos.x = -pos.x;
if(ball.center.y > 460 || ball.center.y < 0)
    pos.y = -pos.y;

}

//在加载视图后实现viewDidLoad以进行其他设置。 - （void）viewDidLoad { pos = CGPointMake（14.0,7.0）;

[NSTimer scheduledTimerWithTimeInterval:0.03 target:self selector:@selector(onTimer) userInfo:nil repeats:YES];

}

Answer 1

您可以使用视图的边界来获取球应该移动的位置，而不是硬编码320和460.

查看bounds的{{1}}属性。

Answer 2

@implementation ViewController {
    BOOL isPositiveXAxis;
    BOOL isPositiveYAxis;
}


- (void)viewDidLoad {
    [super viewDidLoad];

    //By default we are setting both BOOL value to YES because ballImage have (0,0) origin by default 
    isPositiveXAxis = YES;
    isPositiveYAxis = YES;
    imgBallView.layer.cornerRadius = imgBallView.frame.size.width/2;

    [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:@selector(animateBall) userInfo:nil repeats:YES];
}

-(void)animateBall {

        //getting current image transform, and we will modify it later in code
        CGAffineTransform transform = imgBallView.transform;


        //checking if ‘isPositiveXAxis is true and imgBallView xAxis have less value then view border
        if (isPositiveXAxis && imgBallView.frame.origin.x < self.view.frame.size.width - imgBallView.frame.size.width) {
            transform.tx++;
        }
        else {
            isPositiveXAxis = NO;

            if (transform.tx>0) {
                transform.tx--;
            }
            else {
                isPositiveXAxis = YES;
            }
        }

        //checking if ‘isPositiveYAxis is true and imgBallView yAxis have less value then view border
        if (isPositiveYAxis && imgBallView.frame.origin.y < self.view.frame.size.height - imgBallView.frame.size.height) {
            transform.ty++;
        }
        else {
            isPositiveYAxis = NO;

            if (transform.ty>0) {
                transform.ty--;
            }
            else {
                isPositiveYAxis = YES;
            }
        }

        //setting updated trasform to imgBallView it will look animated.
        imgBallView.transform =  transform;
}

上面的代码将生成所需的模式。可以在视频中看到：https://vid.me/G3zO，这可以帮助您更好地理解

iPhone开发-CGPoint＆amp; NSTimer帮助

2 个答案: