百度地图绘制轨迹

最近项目须要作到这个功能，写篇博客，只是自我总结，没有时间写demo，先上效果图：

先说思路，咱们的项目是一秒走一个经纬度及画一条线段，可前进后退，先用定时器重复执行一个方法，方法就处理小点前进的动画，绘制路线我是每次清空，从新绘制的，设置一个全局变量，记录下当下小点移动到哪一个位置，此次好进行前进后退的处理，思路其实很简单的

#pragma mark---------划线代理回调----------
- (BMKOverlayView*)mapView:(BMKMapView *)map viewForOverlay:(id<BMKOverlay>)overlay
{
    if ([overlay isKindOfClass:[BMKPolyline class]]) {
        BMKPolylineView* polylineView = [[BMKPolylineView alloc] initWithOverlay:overlay];
        polylineView.fillColor = [[UIColor cyanColor] colorWithAlphaComponent:1];
        polylineView.strokeColor = [[UIColor blueColor] colorWithAlphaComponent:0.7];
        polylineView.lineWidth = 2.0f;
        return polylineView;
    }
    return nil;
}
复制代码

BMKPointAnnotation * antion = [[BMKPointAnnotation alloc]init];
    antion.title = @"";
    antion.coordinate = _coors[_index-1];
    [_mapView addAnnotation:antion];
    
    
    //重复再添加一次起点和终点
    KJBHomeHistoricalTrackAnnotation * Annotation = [[KJBHomeHistoricalTrackAnnotation alloc]init];
    Annotation.type =0;
    Annotation.coordinate = _coors[0];
    [_mapView addAnnotation:Annotation];
    
    
    Annotation = [[KJBHomeHistoricalTrackAnnotation alloc] init];
    Annotation.type = 1;
    Annotation.coordinate = _coors[Max];
    [_mapView addAnnotation:Annotation];
    //轨迹绘制
    BMKPolyline  * polyline = [BMKPolyline polylineWithCoordinates:_coors count:_index];
    [_mapView addOverlay:polyline];
复制代码

// 根据polyline设置地图范围
- (void)mapViewFitPolyLine:(BMKPolyline *) polyLine {
    CGFloat ltX, ltY, rbX, rbY;
    if (polyLine.pointCount < 1) {
        return;
    }
    BMKMapPoint pt = polyLine.points[0];
    ltX = pt.x; ltY = pt.y;
    rbX = pt.x; rbY = pt.y;
    for (int i = 1; i < polyLine.pointCount; i++) {
        BMKMapPoint pt = polyLine.points[i];
        if (pt.x < ltX) {
            ltX = pt.x;
        }
        if (pt.x > rbX) {
            rbX = pt.x;
        }
        if (pt.y > ltY) {
            ltY = pt.y;
        }
        if (pt.y < rbY) {
            rbY = pt.y;
        }
    }
    BMKMapRect rect;
    rect.origin = BMKMapPointMake(ltX , ltY);
    rect.size = BMKMapSizeMake(rbX - ltX, rbY - ltY);
    [_mapView setVisibleMapRect:rect];
}复制代码

到这里，代码就结束了，在viewWillDisappear中别忘了设置_mapView.delegate为nil，

定时器也要及时释放调