xcode的CGPoint arc4random不工作

我有22張圖片... 11（rightwall1，rightwall2，rightwall3等），其他11（leftwall1，leftwall2，leftwall3等）xcode的CGPoint arc4random不工作

我把每一個ontop的的另一種方法是將它們的y值設置爲之前的牆壁y值加上牆壁的高度（所有牆壁都是相同的高度）。

這工作正常！現在

，我試圖用arc4random設置x的值，這樣他們就活蹦亂跳在一定範圍內的地方......

右壁完美，但左側牆壁，其中一些工作但其中大部分沒有顯示在屏幕上。

我手動將x值設置爲-15，它出現在屏幕上，並且低於arc4random允許的值。

我能想到的唯一問題是我正在減去左牆的錯誤？

下面是設置牆位置的代碼，我在整個項目中沒有其他代碼。

-(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))); 

}

來源

2011-05-30 Albert Renshaw

手動設置一個以-15的x值，並在屏幕上出現了，那就是低於arc4random允許它去。 -60和14之間

((arc4random()%75)-60)收益數字，因爲OHHHHHHHHHHHHHHHH介於0和74

來源

2011-05-30 15:43:26

(arc4random()%75)回報數字！ HAHAHHAHAHAHAHAHHAHAHAAH – 2011-05-30 17:39:54

儘管仍然沒有工作，問題是當處理負arc4random值你不能使用整數你必須使用浮動..如果減去你不能只減去你必須添加arc4random乘以負1 float值。這是因爲arc4random使用我假設的模... – 2011-05-31 04:52:57

arc4random返回無符號值。使用％限制範圍。你不需要浮點數 - 只是在％之後的有符號整數。 – 2011-05-31 11:53:35

xcode的CGPoint arc4random不工作

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