ios detecting line angle or degree

问题:

I'm new to iOS, i am trying to develop a freehand drawing app, using uibezierPath.is there a way to calculate or receive the total line length, even if i drew straight line, curved or a circle. i am using addline on the the touchmove method, and i don't have any control points.

回答1:

Inside your touchesBegan method, you can use this code

{
UITouch * touch = [touches anyObject];
CGPoint present = [touch locationInView:self];
CGPoint previous = [touch previousLocationInView:self];
CGFloat angle = [self getAngle:present :previous];
}

- (float) getAngle:(CGPoint)a :(CGPoint)b
{
    int x = a.x;
    int y = a.y;
    float dx = b.x - x;
    float dy = b.y - y;
    CGFloat radians = atan2(-dx,dy);        // in radians
    CGFloat degrees = radians * 180 / 3.14; // in degrees
    return angle;
}

You can call this method in any method to find the angle between two CGPoints in the UIView.

Hope this helped :-)

回答2:

Irrespective of whether the line is curved or straight, you can find the distance between any two points. (I don't know how to get the length of the line). If the line is straight, the distance between the two points should be equal to that of the line.

Try this code,

- (double)getDistance:(CGPoint)one :(CGPoint)two
{
    return sqrt((two.x - one.x)*(two.x - one.x) + (two.y - one.y)*(two.y - one.y));
}

It's a common method many are familiar with, (sqrt)[(x2-x1)(x2-x1) + (y2-y1)(y2-y1)].

Hope this helps :-)