1 -(void) loadRoute
 2 {
 3 NSString* filePath = [[NSBundle mainBundle] pathForResource:@”route” ofType:@”csv”];
 4 NSString* fileContents = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
 5 NSArray* pointStrings = [fileContents componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
 6 
 7 // while we create the route points, we will also be calculating the bounding box of our route
 8 // so we can easily zoom in on it.
 9 MKMapPoint northEastPoint;
10 MKMapPoint southWestPoint; 
11 
12 // create a c array of points.
13 MKMapPoint* pointArr = malloc(sizeof(CLLocationCoordinate2D) * pointStrings.count);
14 
15 for(int idx = 0; idx < pointStrings.count; idx++)
16 {
17 // break the string down even further to latitude and longitude fields.
18 NSString* currentPointString = [pointStrings objectAtIndex:idx];
19 NSArray* latLonArr = [currentPointString componentsSeparatedByCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@","]];
20 
21 CLLocationDegrees latitude = [[latLonArr objectAtIndex:0] doubleValue];
22 CLLocationDegrees longitude = [[latLonArr objectAtIndex:1] doubleValue];
23 
24 // create our coordinate and add it to the correct spot in the array
25 CLLocationCoordinate2D coordinate = CLLocationCoordinate2DMake(latitude, longitude);
26 
27 MKMapPoint point = MKMapPointForCoordinate(coordinate);
28 
29 //
30 // adjust the bounding box
31 //
32 
33 // if it is the first point, just use them, since we have nothing to compare to yet.
34 if (idx == 0) {
35 northEastPoint = point;
36 southWestPoint = point;
37 }
38 else
39 {
40 if (point.x > northEastPoint.x)
41 northEastPoint.x = point.x;
42 if(point.y > northEastPoint.y)
43 northEastPoint.y = point.y;
44 if (point.x < southWestPoint.x)
45 southWestPoint.x = point.x;
46 if (point.y < southWestPoint.y)
47 southWestPoint.y = point.y;
48 }
49 
50 pointArr[idx] = point;
51 
52 }
53 
54 // create the polyline based on the array of points.
55 self.routeLine = [MKPolyline polylineWithPoints:pointArr count:pointStrings.count];
56 
57 _routeRect = MKMapRectMake(southWestPoint.x, southWestPoint.y, northEastPoint.x -southWestPoint.x, northEastPoint.y - southWestPoint.y);
58 
59 // clear the memory allocated earlier for the points
60 free(pointArr);
61 
62 }
63 将这个路径MKPolyline对象添加到地图上
64 
65 [self.mapView addOverlay:self.routeLine];
66 显示在地图上：
67 
68 - (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id )overlay
69 {
70 MKOverlayView* overlayView = nil;
71 
72 if(overlay == self.routeLine)
73 {
74 //if we have not yet created an overlay view for this overlay, create it now.
75 if(nil == self.routeLineView)
76 {
77 self.routeLineView = [[[MKPolylineView alloc] initWithPolyline:self.routeLine] autorelease];
78 self.routeLineView.fillColor = [UIColor redColor];
79 self.routeLineView.strokeColor = [UIColor redColor];
80 self.routeLineView.lineWidth = 3;
81 }
82 
83 overlayView = self.routeLineView;
84 
85 }
86 
87 return overlayView;
88 
89 }