嗨，我正在做一个必须显示路线地图的应用程序。我解析了一个 Json 以获得绘制折线的点。我在网上找到了一个代码来绘制这条折线。我在此链接上找到的代码：http: //iosguy.com/2012/05/22/tracing-routes-with-mapkit/
在它说“创建 MKPolyline 注释”的地方，我试图在我的应用程序中导入它，但是我在创建坐标数组时遇到了问题。我的方法是这样的：
- (void)createMKpolylineAnnotation {
NSInteger numberOfSteps = self.path.count;
CLLocationCoordinate2D *coords = malloc(sizeof(CLLocationCoordinate2D) * numberOfSteps);
for (NSInteger index = 0; index < numberOfSteps; index++) {
CLLocation *location = [self.path objectAtIndex:index];
CLLocationCoordinate2D coordinate = location.coordinate;
coords[index] = coordinate;
}
MKPolyline *polyLine = [MKPolyline polylineWithCoordinates:coords count:numberOfSteps];
[self.mapView addOverlay:polyLine];
}
当我尝试查看 coords 的值仅是第一次设置时，这是为什么呢？你能帮我解决这个问题还是我应该用另一种模式？
我在这里发布处理地图视图的视图控制器的代码。
MapViewController.h
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
@interface MapViewController : UIViewController <MKMapViewDelegate>
@property (weak, nonatomic) IBOutlet MKMapView *mapView;
@property (nonatomic, strong) NSString *fromCity;
@property (nonatomic, strong) NSString *toCity;
- (IBAction)chooseKindOfMap:(id)sender;
@end
MapViewController.m
#import "MapViewController.h"
#import "AppDelegate.h"
#import "PlaceAnnotation.h"
@interface MapViewController ()
@property (nonatomic, strong)NSMutableArray *mapAnnotation;
@property (nonatomic) BOOL needUpdateRegion;
@property (nonatomic, strong)NSMutableArray *path;
@end
@implementation MapViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
[self parseGoogleJsonToObtainPointsForPolyline];
[self.mapView setDelegate:self];
self.needUpdateRegion = YES;
//[self centerMap];
self.mapAnnotation = [[NSMutableArray alloc]initWithCapacity:2];
AppDelegate *appDelegate = (AppDelegate*)[[UIApplication sharedApplication]delegate];
NSLog(@"%d", appDelegate.dataForMap.count);
NSArray* coords = [self getCoords:appDelegate.dataForMap];
NSLog(@"coords = %@", coords);
PlaceAnnotation *fromPlace = [[PlaceAnnotation alloc] initWithCoordinateAndName:coords[0] andLong:coords[1] andName:self.fromCity];
PlaceAnnotation *toPlace = [[PlaceAnnotation alloc] initWithCoordinateAndName:coords[2] andLong:coords[3] andName:self.toCity];
[self.mapAnnotation insertObject:fromPlace atIndex:0];
[self.mapAnnotation insertObject:toPlace atIndex:1];
NSLog(@"mapAnnotation.count: %d", self.mapAnnotation.count);
if (self.mapAnnotation) {
[self.mapView removeAnnotations:self.mapView.annotations];
}
[self.mapView addAnnotation:self.mapAnnotation[0]];
[self.mapView addAnnotation:self.mapAnnotation[1]];
NSLog(@"MapAnnotation = %@", self.mapView.annotations);
[self updateRegion];
[self createMKpolylineAnnotation];
}
//- (void)viewDidAppear:(BOOL)animated {
// [super viewDidAppear:animated];
// if (self.needUpdateRegion) [self updateRegion];
//}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (MKAnnotationView*)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation {
MKPinAnnotationView *pin = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:nil];
pin.pinColor = MKPinAnnotationColorRed;
return pin;
}
- (void)mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views {
MKPinAnnotationView *ulv = [mapView viewForAnnotation:mapView.userLocation];
ulv.hidden = YES;
}
- (NSArray*)getCoords:(NSDictionary*)data {
NSArray *legs = [data objectForKey:@"legs"];
NSDictionary *firstZero = [legs objectAtIndex:0];
NSDictionary *endLocation = [firstZero objectForKey:@"end_location"];
NSDictionary *startLocation = [firstZero objectForKey:@"start_location"];
NSString *latFrom = [startLocation objectForKey:@"lat"];
NSString *lngFrom = [startLocation objectForKey:@"lng"];
NSString *latTo = [endLocation objectForKey:@"lat"];
NSString *lngTo = [endLocation objectForKey:@"lng"];
return @[latFrom,lngFrom,latTo,lngTo];
}
- (void)centerMap {
MKCoordinateRegion region;
region.center.latitude = 41.178654;
region.center.longitude = 11.843262;
region.span.latitudeDelta = 11.070406;
region.span.longitudeDelta = 12.744629;
[self.mapView setRegion:region];
}
- (IBAction)chooseKindOfMap:(id)sender {
if ([sender tag] == 0) {
self.mapView.mapType = MKMapTypeStandard;
}
if ([sender tag] == 1) {
self.mapView.mapType = MKMapTypeSatellite;
}
if ([sender tag] == 2) {
self.mapView.mapType = MKMapTypeHybrid;
}
}
- (void)updateRegion
{
self.needUpdateRegion = NO;
CGRect boundingRect;
BOOL started = NO;
for (id <MKAnnotation> annotation in self.mapView.annotations) {
CGRect annotationRect = CGRectMake(annotation.coordinate.latitude, annotation.coordinate.longitude, 0, 0);
if (!started) {
started = YES;
boundingRect = annotationRect;
} else {
boundingRect = CGRectUnion(boundingRect, annotationRect);
}
}
if (started) {
boundingRect = CGRectInset(boundingRect, -0.2, -0.2);
if ((boundingRect.size.width < 20) && (boundingRect.size.height < 20)) {
MKCoordinateRegion region;
region.center.latitude = boundingRect.origin.x + boundingRect.size.width / 2;
region.center.longitude = boundingRect.origin.y + boundingRect.size.height / 2;
region.span.latitudeDelta = boundingRect.size.width;
region.span.longitudeDelta = boundingRect.size.height;
[self.mapView setRegion:region animated:YES];
}
}
}
- (void)parseGoogleJsonToObtainPointsForPolyline {
NSDictionary *polyline;
NSMutableArray *points = [[NSMutableArray alloc]init];;
AppDelegate *appDelegate = (AppDelegate*)[[UIApplication sharedApplication]delegate];
NSArray *legs = [appDelegate.dataForMap objectForKey:@"legs"];
NSDictionary *firstZero =[legs objectAtIndex:0];
NSArray *steps = [firstZero objectForKey:@"steps"];
for (int i = 0; i < steps.count; i++) {
polyline = [steps[i] objectForKey:@"polyline"];
[points addObject:polyline[@"points"]];
NSLog(@"POINTS = %@", polyline[@"points"]);
self.path = [self decodePolyLine:points[i]];
}
NSLog(@"path = %@", self.path);
}
-(NSMutableArray *)decodePolyLine:(NSString *)encodedStr {
NSMutableString *encoded = [[NSMutableString alloc] initWithCapacity:[encodedStr length]];
[encoded appendString:encodedStr];
[encoded replaceOccurrencesOfString:@"\\\\" withString:@"\\"
options:NSLiteralSearch
range:NSMakeRange(0, [encoded length])];
NSInteger len = [encoded length];
NSInteger index = 0;
NSMutableArray *array = [[NSMutableArray alloc] init];
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];
NSNumber *longitude = [[NSNumber alloc] initWithFloat:lng * 1e-5];
CLLocation *location = [[CLLocation alloc] initWithLatitude:[latitude floatValue] longitude:[longitude floatValue]];
[array addObject:location];
}
return array;
}
- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay {
MKPolylineView *polylineView = [[MKPolylineView alloc] initWithPolyline:overlay];
polylineView.strokeColor = [UIColor redColor];
polylineView.lineWidth = 1.0;
return polylineView;
}
- (void)createMKpolylineAnnotation {
NSInteger numberOfSteps = self.path.count;
CLLocationCoordinate2D *coords = malloc(sizeof(CLLocationCoordinate2D) * numberOfSteps);
for (NSInteger index = 0; index < numberOfSteps; index++) {
CLLocation *location = [self.path objectAtIndex:index];
CLLocationCoordinate2D coordinate = location.coordinate;
coords[index] = coordinate;
}
MKPolyline *polyLine = [MKPolyline polylineWithCoordinates:coords count:numberOfSteps];
[self.mapView addOverlay:polyLine];
}
@end
我使用 AppDelegate 拥有 Json（我在另一个类中解析它）