CGPoint讓iphone的問題？

Question

在我的遊戲中，我有一隻鳥在一個框架內飛行，但我只能讓它們飛向兩個不同的方向。如果有2只鳥，它們會朝兩個不同的方向前進。如果有3只鳥，其中2只朝一個方向，另一隻朝不同方向。我想讓這些鳥隨機進入四個不同的方向。右上，左下，左下，這是我的代碼。

-(void) AddBirdIntoArray: (int) BirdCount { 
for(int i=0; i< BirdCount ; i++){ 


    if(appDelegate.enemyselect == 0){ 

    imgBird[i]=[[UIImageView alloc] initWithImage:firstImage]; 
    [imgBird[i] setAnimationImages:birdArrayConstant]; 
    } 

    else if(appDelegate.enemyselect == 1){ 

    imgBird[i]=[[UIImageView alloc] initWithImage:firstImagegreenorange]; 
    [imgBird[i] setAnimationImages:birdArrayConstant3]; 
    } 

    else if(appDelegate.enemyselect == 2){ 
    imgBird[i]=[[UIImageView alloc] initWithImage:firstImageblueyellow]; 
    [imgBird[i] setAnimationImages:birdArrayConstant4]; 
    } 

    else if(appDelegate.enemyselect == 3){ 
    imgBird[i]=[[UIImageView alloc] initWithImage:firstImagebluewhite]; 
    [imgBird[i] setAnimationImages:birdArrayConstant2]; 
    } 

    else if(appDelegate.enemyselect == 4){ 
    imgBird[i]=[[UIImageView alloc] initWithImage:firstImagepinkpurple]; 
    [imgBird[i] setAnimationImages:birdArrayConstant5]; 
    } 

    else if(appDelegate.enemyselect == 5){ 
    imgBird[i]=[[UIImageView alloc] initWithImage:firstImagebluegreen]; 
    [imgBird[i] setAnimationImages:birdArrayConstant6]; 
    } 

    else if(appDelegate.enemyselect == 6){ 
    imgBird[i]=[[UIImageView alloc] initWithImage:firstImageorangewhite]; 
    [imgBird[i] setAnimationImages:birdArrayConstant7]; 
    } 

    else if(appDelegate.enemyselect == 7){ 
    imgBird[i]=[[UIImageView alloc] initWithImage:firstImageredblue]; 
    [imgBird[i] setAnimationImages:birdArrayConstant8]; 
    } 



    [imgBird[i] setAnimationDuration:1.0]; 
    [imgBird[i] startAnimating]; 

    if(i%2==0){ 
    pos[i]=CGPointMake(-1,1); 
    } 

    else{ 
    pos[i]=CGPointMake(1,-1); 
    } 

    xvalue = arc4random()%250; 
    yvalue = arc4random()%250; 
    CGRect TempRect = CGRectMake(xvalue ,yvalue , 22 , 22); 
    imgBird[i].frame = TempRect; 
    [birdImageViewArray addObject:imgBird[i]]; 
    [self addSubview:imgBird[i]]; 
    [imgBird[i] release]; 
    } 




[birdArray release]; 
} 

Answer 1

我覺得這些都是你的兩個方向向量：

pos[i]=CGPointMake(-1,1); 
pos[i]=CGPointMake(1,-1); 

其他兩個方向：

pos[i]=CGPointMake(-1,-1); 
pos[i]=CGPointMake(1,1); 

，當然，而不是如果基於i%2 /其他，你應該使用一個開關：

arc4random()%4