iOS实现滑动弧形菜单的思路与方法

if(pgr.state==UIGestureRecognizerStateBegan){

  self.endMove = NO;

  self.beginPoint=[pgr locationInView:self];

 }else if (pgr.state==UIGestureRecognizerStateChanged){
  self.movePoint= [pgr locationInView:self];

  self.moveX = sqrt(fabs(self.movePoint.x - self.beginPoint.x) * fabs(self.movePoint.x - self.beginPoint.x) + fabs(self.movePoint.y - self.beginPoint.y) * fabs(self.movePoint.y - self.beginPoint.y));
}

if (self.movePoint.x>self.beginPoint.x) {
   self.moveNum += self.moveX;
  } else{
   self.moveNum -= self.moveX;
  }

if (self.moveNum > 0) {
   self.moveNum = 0;
  }

  if (self.moveNum < -((SCREEN_WIDTH - 20 - subViewW)/(self.showBtnCount - 1)) * (self.subViewArray.count - self.showBtnCount)) {
   self.moveNum = -((SCREEN_WIDTH - 20 - subViewW)/(self.showBtnCount - 1)) * (self.subViewArray.count - self.showBtnCount);
  }

 ///中心点
 CGFloat yy = 0.0;
 CGFloat xx = 0.0;
 CGFloat margin = 0.0;
 ///子视图x中点
 UIView *view = self.subViewArray[0];
 CGFloat subCenterX = view.frame.size.width / 2;

 for (NSInteger i=0; i<self.subViewArray.count ;i++) {// 178,245

  margin = i * ((SCREEN_WIDTH - 20 - view.frame.size.width)/(self.showBtnCount - 1));

  xx = 10 + subCenterX + fabs(self.subViewX) + margin + self.moveNum;

  yy = sqrt((self.radius - self.circleMargin / 2) * (self.radius - self.circleMargin / 2) - (xx - self.radius) * (xx - self.radius)) + self.radius;

  if (xx >= self.radius - (self.radius - self.circleMargin / 2) && xx <= self.radius + (self.radius - self.circleMargin / 2)) {

   UIButton *button=[self.subViewArray objectAtIndex:i];
   NSLog(@"~~~~~~~%@",button);
   if (self.isEndMove) {
    [UIView animateWithDuration:0.3 animations:^{
     button.center=CGPointMake(xx , yy);
    }];
   } else{
    button.center=CGPointMake(xx , yy);
   }
  }
  NSLog(@"xx:%f---------yy:%f",xx,yy);
 }