函数fitMap视图到注解列表（注解：[MKPointAnnotation]，用户位置：CL位置坐标2D）-〉空{让Map边缘填充= UI边缘插入（顶部：20，左侧：20，底部：20，右：20）变量缩放矩形：MKMap矩形= MKMap矩形空

for index in 0..<annotations.count {
        let annotation = annotations[index]
        let aPoint:MKMapPoint = MKMapPointForCoordinate(annotation.coordinate)
        let rect:MKMapRect = MKMapRectMake(aPoint.x, aPoint.y, 0.1, 0.1)

        if MKMapRectIsNull(zoomRect) {
            zoomRect = rect
        } else {
            zoomRect = MKMapRectUnion(zoomRect, rect)
        }
    }

    let aPoint:MKMapPoint = MKMapPointForCoordinate(userLocation)
    let rect:MKMapRect = MKMapRectMake(aPoint.x, aPoint.y, 0.1, 0.1)

    if MKMapRectIsNull(zoomRect) {
        zoomRect = rect
    } else {
        zoomRect = MKMapRectUnion(zoomRect, rect)
    }
    mapView.setVisibleMapRect(zoomRect, edgePadding: mapEdgePadding, animated: true)
}