大家無論在玩王者榮耀，還是絕地求生等升級版的游戲時，都會遇到游戲操作控制盤。

基于此，個人開發了一個簡易的操作盤，主要包括兩個部分：操作控制臺背景 和 中間操作圓球。

基于此，定義：consoleBGImageView，放置一張初始Image；定義中間操作圓球為：rotateButton

通過約束條件，來控制rotateButton只能在consoleBGImageView范圍內轉動

通過UIPanGestureRecognizer添加rotateButton拖動手勢，當轉動到不同的方向時，修改相應的背景圖，這樣可以知道轉動到哪個方向。

通過如下代碼，控制手指觸碰的點限制在圓盤內部

-(void)rotateLocation:(CGPoint)pLocation {
    if([self IfYuntaiViewIsIntheBigView:pLocation]){
        self.rotateButton.center = CGPointMake(pLocation.x, pLocation.y);
        
        CGPoint tranPoint = CGPointMake(pLocation.x - centerViewX, pLocation.y - centerViewY);
        ELPCircleConsoleMoveDirection direction = [self determineCameraDirection:tranPoint];
        currentDirection = direction;
    } else {
        CGFloat radius = self.traceView.size.width * 0.5;
        CGPoint pointc = self.consoleBGImageView.center;
        CGPoint changePoint = [self CirclePoint:radius withCenterCircle:pointc withCurrentPoint:pLocation];
        
        self.rotateButton.center = CGPointMake(changePoint.x, changePoint.y);
        
        CGPoint tranPoint = CGPointMake(changePoint.x - centerViewX, changePoint.y - centerViewY);
        ELPCircleConsoleMoveDirection direction = [self determineCameraDirection:tranPoint];
        currentDirection = direction;
    }
    
    CGFloat xValue = fabs(self.rotateButton.centerX - centerViewX);
    CGFloat yValue = fabs(self.rotateButton.centerY - centerViewY);
    
    CGFloat currentRadiusValue = xValue * xValue + yValue * yValue;
    CGFloat bgImgRadiusWith = self.consoleBGImageView.width * 0.5 * 0.5;
    if(currentRadiusValue > bgImgRadiusWith * bgImgRadiusWith * 0.6) {
        [self sendRotateButtonRotateCmd];
    } else {
        [self resumBackgroundImgToNormal];
    }
}

詳細代碼詳見如下鏈接，如果對你有幫助，麻煩star一個，謝謝。
https://github.com/ElsonPeng/ELPCircleConsoleView

效果圖如下：

screenshot.png

Simulator Screen Shot - iPhone 8 Plus - 2018-03-04 at 22.43.55.png