如何使用 SpriteKit 在 Xcode 6 中通过滑动找到角度？

Question

我正在制作两款游戏，对于这两款游戏，我想知道如何通过滑动找到角度。我听说你使用

UIPanGesutre

，但我不知道如何使用它。有什么帮助吗？

Answer 1

您可以检测触摸的起始和停止位置坐标，并计算出两点之间的角度。

Answer 2

在

touchesBegan

事件中，确定触摸位置：

在界面中创建一个名为

initialLocation

类型为

CGPoint

的实例变量

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    //Determine touch location and store in instance variable (so you can use it again in touchesEnded)
    UITouch *touch = [touches anyObject];
    initialLocation = [touch locationInNode:self];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
    //Determine touch location
    UITouch *touch = [touches anyObject];
    CGPoint finalLocation = [touch locationInNode:self];

    //Find change in x and y between the touches
    CGFloat changeX = finalLocation.x - initialLocation.x;
    CGFloat changeY = finalLocation.y - initialLocation.y;

    //Use trig to find angle (note this angle is in radians)
    float radians = atan(changeY/changeX);

    //Convert to degrees
    float degrees = 360 * radians/(2 * M_PI);

    //*Note* you would have to alter this part depending on where you are measuring your angle from (I am using the standard counterclockwise from right)
    //This step is due to the limitation of the atan function
    float angle;
    if (changeX > 0 && changeY > 0){
        angle = degrees;
    }
    else if (changeX < 0 && changeY > 0){
        angle = 180 + degrees;
    }
    else if (changeX < 0 && changeY < 0){
        angle = 180 + degrees;
    }
    else{
        angle = 360 + degrees;
    }
    NSLog(@"Now: %f",angle);
    //^^^ HERE IS THE ANGLE! ^^^

}

我希望这有帮助！