xcode CGPoint arc4random 不工作

Question

我有 22 个图像... 11 个是（rightwall1、rightwall2、rightwall3 等），其他 11 个是（leftwall1、leftwall2、leftwall3 等）

我通过将它们的 y 值设置为前一堵墙 y 将每个图像放置在另一个图像的上面值加上墙的高度（所有墙的高度相同）。

这很好用！

现在，我试图使用 arc4random 设置 x 值，这样它们就会在一定范围内跳遍各处...

右墙工作完美，但左墙，其中一些可以工作，但大多数不显示出现在屏幕上。

我手动将 x 值 1 设置为 -15，它显示在屏幕上，并且低于 arc4random 允许它运行的值。

我能想到的唯一问题是我减去左墙的错误？

这是设置墙壁位置的代码，我在整个项目中还没有其他代码。

-(void)awakeFromNib {

    rightWall1.center = CGPointMake( ((arc4random()%75)+330), (460-((rightWall1.frame.size.height)/2)) );//460 = bottom of screen
    rightWall2.center = CGPointMake( ((arc4random()%75)+330), ((rightWall1.center.y)-(rightWall2.frame.size.height)) );
    rightWall3.center = CGPointMake( ((arc4random()%75)+330), ((rightWall2.center.y)-(rightWall3.frame.size.height)) );
    rightWall4.center = CGPointMake( ((arc4random()%75)+330), ((rightWall3.center.y)-(rightWall4.frame.size.height)) );
    rightWall5.center = CGPointMake( ((arc4random()%75)+330), ((rightWall4.center.y)-(rightWall5.frame.size.height)) );
    rightWall6.center = CGPointMake( ((arc4random()%75)+330), ((rightWall5.center.y)-(rightWall6.frame.size.height)) );
    rightWall7.center = CGPointMake( ((arc4random()%75)+330), ((rightWall6.center.y)-(rightWall7.frame.size.height)) );
    rightWall8.center = CGPointMake( ((arc4random()%75)+330), ((rightWall7.center.y)-(rightWall8.frame.size.height)) );
    rightWall9.center = CGPointMake( ((arc4random()%75)+330), ((rightWall8.center.y)-(rightWall9.frame.size.height)) );
    rightWall10.center = CGPointMake( ((arc4random()%75)+330), ((rightWall9.center.y)-(rightWall10.frame.size.height)) );
    rightWall11.center = CGPointMake( ((arc4random()%75)+330), ((rightWall10.center.y)-(rightWall11.frame.size.height)) );


    leftWall1.center = CGPointMake( ((arc4random()%75)-60), (460-((leftWall1.frame.size.height)/2)) );
    leftWall2.center = CGPointMake( ((arc4random()%75)-60), ((leftWall1.center.y)-(leftWall2.frame.size.height)) );
    leftWall3.center = CGPointMake( ((arc4random()%75)-60), ((leftWall2.center.y)-(leftWall3.frame.size.height)) );
    leftWall4.center = CGPointMake( ((arc4random()%75)-60), ((leftWall3.center.y)-(leftWall4.frame.size.height)) );
    leftWall5.center = CGPointMake( ((arc4random()%75)-60), ((leftWall4.center.y)-(leftWall5.frame.size.height)) );
    leftWall6.center = CGPointMake( ((arc4random()%75)-60), ((leftWall5.center.y)-(leftWall6.frame.size.height)) );
    leftWall7.center = CGPointMake( ((arc4random()%75)-60), ((leftWall6.center.y)-(leftWall7.frame.size.height)) );
    leftWall8.center = CGPointMake( ((arc4random()%75)-60), ((leftWall7.center.y)-(leftWall8.frame.size.height)) );
    leftWall9.center = CGPointMake( ((arc4random()%75)-60), ((leftWall8.center.y)-(leftWall9.frame.size.height)) );
    leftWall10.center = CGPointMake( ((arc4random()%75)-60), ((leftWall9.center.y)-(leftWall10.frame.size.height)) );
    leftWall11.center = CGPointMake( ((arc4random()%75)-60), ((leftWall10.center.y)-(leftWall11.frame.size.height)) );

}

Answer 1

我手动将 x 值 1 设置为 -15，它显示在屏幕上，并且低于 arc4random 允许的值。

((arc4random()%75)-60) 返回 -60 到 14 之间的数字，因为 (arc4random()%75) 返回 0 到 74 之间的数字。