// you must set both of these
CGPoint centerOfCircle;
float radius;

int count = 0;
float angleStep = 2.0f * M_PI / [arrayOfViews count];

for (UIView *view in arrayOfViews) {
    float xPos = cosf(angleStep * count) * radius;
    float yPos = sinf(angleStep * count) * radius;
    view.center = CGPointMake(centerOfCircle.x + xPos, centerOfCircle.y +yPos);
    count++;
}

// These calculate the x and y offset from the center by using the angle in radians
#define LengthDir_X(__Length__,__Direction__) (cos(__Direction__)*__Length__)
#define LengthDir_Y(__Length__,__Direction__) (sin(__Direction__)*__Length__)

// I use this to convert degrees to radians and back if I have to
#define DegToRad(__ANGLE__) (((__ANGLE__) * 2.0 * M_PI) / 360.0)
#define RadToDeg(__ANGLE__) (((__ANGLE__) * 360) / (2.0 * M_PI))