iOS高德地图让指定区域或者点显示在屏幕中间

//加入所有圆的点
//设置位置的点
                CLLocationCoordinate2D destinationCoordinated =CLLocationCoordinate2DMake(latitude,longitude);

                MAPointAnnotation * a1= [[MAPointAnnotation alloc] init];
                a1.coordinate =destinationCoordinated;

                // 111000 这个是米转换经纬度的最大尺度，所以算出来的点只会在圆之外
                double jingwei = (double) areaRadius/111000;
              //计入一个中心点
                [arraySpace addObject:a1];

               //由原点计算上下左右的四个点
                for (int i=0; i<4; i++) {
                    MAPointAnnotation * a1= [[MAPointAnnotation alloc] init];
                    switch (i) {
                        case 0:
                            NSLog(@"%lf----%lf",latitude+jingwei,longitude+jingwei);
                            a1.coordinate = CLLocationCoordinate2DMake(latitude+jingwei,longitude);
                            
                            break;
                            
                        case 1:
                            a1.coordinate = CLLocationCoordinate2DMake(latitude-jingwei,longitude);
                            break;
                            
                        case 2:
                            a1.coordinate = CLLocationCoordinate2DMake(latitude,longitude+jingwei);
                            break;
                            
                        case 3:
                            a1.coordinate = CLLocationCoordinate2DMake(latitude,longitude-jingwei);
                            break;
                            
                        default:
                            break;
                    }
                    
                    
                    //加入数组
                    [arraySpace addObject:a1];
                }