MKMapView类——获取并绘制两点之间的路线

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- (id) initWithFrame:(CGRect) frame{    self = [super initWithFrame:frame];    if (self) {        mapView = [[MKMapView alloc] initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];        mapView.showsUserLocation = YES;        [mapView setDelegate:self];        [self addSubview:mapView];        routeView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, mapView.frame.size.width, mapView.frame.size.height)];        routeView.userInteractionEnabled = NO;        [mapView addSubview:routeView];                self.lineColor = [UIColor redColor];    }    return self;}//显示两点之间的线路-(void) showRouteFrom: (Place*) f to:(Place*) t {        if(routes) {        [mapView removeAnnotations:[mapView annotations]];        [routes release];    }        PlaceMark* from = [[[PlaceMark alloc] initWithPlace:f] autorelease];    PlaceMark* to = [[[PlaceMark alloc] initWithPlace:t] autorelease];        [mapView addAnnotation:from];    [mapView addAnnotation:to];        //计算出两点之间的线路所包含的点的数组    routes = [[self calculateRoutesFrom:from.coordinate to:to.coordinate] retain];    //根据数组画线    [self updateRouteView];    //根据线路确定呈现范围    [self centerMap];}-(NSArray*) calculateRoutesFrom:(CLLocationCoordinate2D) f to: (CLLocationCoordinate2D) t {    NSString* saddr = [NSString stringWithFormat:@"%f,%f", f.latitude, f.longitude];    NSString* daddr = [NSString stringWithFormat:@"%f,%f", t.latitude, t.longitude];        NSString* apiUrlStr = [NSString stringWithFormat:@"http://maps.google.com/maps?output=dragdir&saddr=%@&daddr=%@", saddr, daddr];    NSURL* apiUrl = [NSURL URLWithString:apiUrlStr];    NSLog(@"\n api url: %@", apiUrl);    NSString *apiResponse = [NSString stringWithContentsOfURL:apiUrl encoding:NSASCIIStringEncoding error:nil];    NSString* encodedPoints = [apiResponse stringByMatching:@"points:\\\"([^\\\"]*)\\\"" capture:1L];    NSLog(@"\n %@",encodedPoints);    return [self decodePolyLine:[encodedPoints mutableCopy]];}/* {tooltipHtml:" (23.4\x26#160;km / 25 mins)",    polylines:[{id:"route0",       points:"{ntrFopdfU?rv@ZrcB??UzALrE??Ot@@bG??e@\\oF?cCp@u@???gCf@yu@C??wuAEaKHkJb@eHx@eGrA_EpAyHrDyEdDcGtFyErF_J|Mgb@dt@??yfB||Cw@bB}ApEcLv`@uBnIcAdGOjBS|Gt@bhArA`yA??rBd~BAdOHxJb@rQDhLJpD|ArkB^fWrA|sAdApm@??v@na@jCpjC??m@nDXvQ??lH_@??BbA??_@V",       levels:"B?BB?BB?BB???BB?BB?@???A???@?BB@???A??@?BB?????????BB?BB?BBBBBBB",    numLevels:4,zoomFactor:16}]}   {ntrFopdfU?rv@ZrcB??UzALrE??Ot@@bG??e@\\oF?cCp@u@???gCf@yu@C??wuAEaKHkJb@eHx@eGrA_EpAyHrDyEdDcGtFyErF_J|Mgb@dt@??yfB||Cw@bB}ApEcLv`@uBnIcAdGOjBS|Gt@bhArA`yA??rBd~BAdOHxJb@rQDhLJpD|ArkB^fWrA|sAdApm@??v@na@jCpjC??m@nDXvQ??lH_@??BbA??_@V*///解码算法(将获取的字符串转码为地图上的坐标位置,并以此构建每一个CLLocation位置对象,然后加入数组 -(NSMutableArray *)decodePolyLine: (NSMutableString *)encoded {        //替换字符串中的@"\\" 为 @"\\\\" ,检索方式为逐个字符,范围是整个字符串    [encoded replaceOccurrencesOfString:@"\\\\"                             withString:@"\\"                                options:NSLiteralSearch                                  range:NSMakeRange(0, [encoded length])];        NSInteger len = [encoded length];    NSInteger index = 0;    NSMutableArray *array = [[[NSMutableArray alloc] init] autorelease];    NSInteger lat=0;    NSInteger lng=0;    while (index < len) {        NSInteger b;        NSInteger shift = 0;        NSInteger result = 0;        do {            b = [encoded characterAtIndex:index++] - 63;            result |= (b & 0x1f) << shift;            shift += 5;        } while (b >= 0x20);        NSInteger dlat = ((result & 1) ? ~(result >> 1) : (result >> 1));        lat += dlat;        shift = 0;        result = 0;        do {            b = [encoded characterAtIndex:index++] - 63;            result |= (b & 0x1f) << shift;            shift += 5;        } while (b >= 0x20);        NSInteger dlng = ((result & 1) ? ~(result >> 1) : (result >> 1));        lng += dlng;        NSNumber *latitude = [[[NSNumber alloc] initWithFloat:lat * 1e-5] autorelease];        NSNumber *longitude = [[[NSNumber alloc] initWithFloat:lng * 1e-5] autorelease];        printf("[%f,", [latitude doubleValue]);        printf("%f]", [longitude doubleValue]);        CLLocation *loc = [[[CLLocation alloc] initWithLatitude:[latitude floatValue]                                                      longitude:[longitude floatValue]] autorelease];        [array addObject:loc];    }    return array;}//用routes数组的内容 确定region的呈现范围-(void) centerMap {    MKCoordinateRegion region;    CLLocationDegrees maxLat = -90;    CLLocationDegrees maxLon = -180;    CLLocationDegrees minLat = 90;    CLLocationDegrees minLon = 180;    for(int idx = 0; idx < routes.count; idx++)    {        CLLocation* currentLocation = [routes objectAtIndex:idx];        if(currentLocation.coordinate.latitude > maxLat)            maxLat = currentLocation.coordinate.latitude;        if(currentLocation.coordinate.latitude < minLat)            minLat = currentLocation.coordinate.latitude;        if(currentLocation.coordinate.longitude > maxLon)            maxLon = currentLocation.coordinate.longitude;        if(currentLocation.coordinate.longitude < minLon)            minLon = currentLocation.coordinate.longitude;    }    region.center.latitude     = (maxLat + minLat) / 2;    region.center.longitude    = (maxLon + minLon) / 2;    region.span.latitudeDelta  = maxLat - minLat;    region.span.longitudeDelta = maxLon - minLon;        [mapView setRegion:region animated:YES];}//用routes数组的内容 画线-(void) updateRouteView {    CGContextRef context = CGBitmapContextCreate(nil,                                                 routeView.frame.size.width,                                                   routeView.frame.size.height,                                                   8,                                                   4 * routeView.frame.size.width,                                                  CGColorSpaceCreateDeviceRGB(),                                                  kCGImageAlphaPremultipliedLast);        CGContextSetStrokeColorWithColor(context, lineColor.CGColor);    CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1.0);    CGContextSetLineWidth(context, 3.0);        for(int i = 0; i < routes.count; i++) {        CLLocation* location = [routes objectAtIndex:i];        CGPoint point = [mapView convertCoordinate:location.coordinate toPointToView:routeView];                if(i == 0) {            CGContextMoveToPoint(context, point.x, routeView.frame.size.height - point.y);        } else {            CGContextAddLineToPoint(context, point.x, routeView.frame.size.height - point.y);        }    }        CGContextStrokePath(context);        CGImageRef image = CGBitmapContextCreateImage(context);    UIImage* img = [UIImage imageWithCGImage:image];        routeView.image = img;    CGContextRelease(context);}#pragma mark mapView delegate functions- (void)mapView:(MKMapView *)mapView regionWillChangeAnimated:(BOOL)animated{    routeView.hidden = YES;}- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated{    [self updateRouteView];    routeView.hidden = NO;    [routeView setNeedsDisplay];}- (void)dealloc {    if(routes) {        [routes release];    }    [mapView release];    [routeView release];    [super dealloc];}

#import <Foundation/Foundation.h>@interface Place : NSObject {    NSString* name;    NSString* description;    double latitude;    double longitude;}@property (nonatomic, retain) NSString* name;@property (nonatomic, retain) NSString* description;@property (nonatomic) double latitude;@property (nonatomic) double longitude;@end#import "Place.h"@implementation Place@synthesize name;@synthesize description;@synthesize latitude;@synthesize longitude;- (void) dealloc{    [name release];    [description release];    [super dealloc];}@end

#import <Foundation/Foundation.h>#import <MapKit/MapKit.h>#import "Place.h"@interface PlaceMark : NSObject <MKAnnotation> {    CLLocationCoordinate2D coordinate;    Place* place;}@property (nonatomic, readonly) CLLocationCoordinate2D coordinate;@property (nonatomic, retain) Place* place;-(id) initWithPlace: (Place*) p;@end#import "PlaceMark.h"@implementation PlaceMark@synthesize coordinate;@synthesize place;-(id) initWithPlace: (Place*) p{    self = [super init];    if (self != nil) {        coordinate.latitude = p.latitude;        coordinate.longitude = p.longitude;        self.place = p;    }    return self;}- (NSString *)subtitle{    return self.place.description;}- (NSString *)title{    return self.place.name;}- (void) dealloc{    [place release];    [super dealloc];}@end