使用 NSDictionary 在地图上添加注释？

Question

感谢您提前提供的帮助...在过去的几个小时里，这个帮助一直困扰着我。

我目前正在提取 JSON feed 并将其存储在 NSDictionary & 中。 NSArray。我试图为每个被拉入的项目添加注释（时间、类型、纬度和经度）。到目前为止，我可以从数组中提取每个值，并在控制台中使用“for”重复它们（请参见下面的代码）。

如何将这些值存储为注释？任何帮助都会很棒。

下面是我失败的尝试...

---

- (void)viewDidLoad {
  [super viewDidLoad];

 // Download JSON Feed
 NSDictionary *feed = [self downloadFeed];
 NSArray *streams = (NSArray *)[feed valueForKey:@"stream"];


 [mapView setMapType:MKMapTypeStandard];
 [mapView setZoomEnabled:YES];
 [mapView setScrollEnabled:YES];
 MKCoordinateRegion region = { {0.0, 0.0 }, { 0.0, 0.0 } }; 
 region.center.latitude = 29.719023;
 region.center.longitude = -114.157110;
 region.span.longitudeDelta = 0.01f;
 region.span.latitudeDelta = 0.01f;
 [mapView setRegion:region animated:YES]; 

 [mapView setDelegate:self];

 int Info;
 for (Info = 0; Info < streams.count; Info++) {
  NSDictionary *stream = (NSDictionary *)[streams objectAtIndex:Info];
  NSLog(@"Time: %@", [stream valueForKey:@"TheTime"]); 
  NSLog(@"Type: %@", [stream valueForKey:@"Type"]); 
  NSLog(@"Longitude: %@", [stream valueForKey:@"Longitude"]); 
  NSLog(@"Latitude: %@", [stream valueForKey:@"Latitude"]); 

  NSString *getLat = [[NSString alloc] initWithFormat: @"%@", [stream valueForKey:@"Latitude"]];
  NSString *getLong = [[NSString alloc] initWithFormat: @"%@", [stream valueForKey:@"Longitude"]];

  NSString *getCoord = [[NSString alloc] initWithFormat: @"{%@,%@}", getLat, getLong];
  getCoordinates = getCoord;


  DisplayMap *ann = [[DisplayMap alloc] init]; 
  ann.title = @"%@", [stream valueForKey:@"TheTime"];
  ann.subtitle = @"%@", [stream valueForKey:@"Type"]; 
  ann.coordinate = getCoordinates;

  [mapView addAnnotation:ann];

  }
}

的代码

这是 DisplayMap DisplayMap.h

#import <Foundation/Foundation.h>
#import <MapKit/MKAnnotation.h>


@interface DisplayMap : NSObject <MKAnnotation> {

    CLLocationCoordinate2D coordinate; 
    NSString *title; 
    NSString *subtitle;
    }

@property (nonatomic, copy) NSString *title; 
@property (nonatomic, copy) NSString *subtitle;

@property (nonatomic, readonly) CLLocationCoordinate2D coordinate; 


@end

，现在是 DisplayMap.m

#import "DisplayMap.h"

@implementation DisplayMap

@synthesize coordinate;
@synthesize title;
@synthesize subtitle;


-(void)dealloc{
    [title release];
    [super dealloc];
    }

@end

Answer 1

获取坐标是什么类型？不管怎样，它肯定没有被正确初始化。

假设您将纬度和经度作为字符串存储在字典中，这应该可以解决问题。

double lat = [[stream valueForKey:@"Latitude"] doubleValue];
double lon = [[stream valueForKey:@"Longitude"] doubleValue];
CLLocationCoordinate2D coord = { lat, lon };

DisplayMap *ann = [[DisplayMap alloc] init]; 
ann.title = [stream valueForKey:@"TheTime"];
ann.subtitle = [stream valueForKey:@"Type"]; 
ann.coordinate = coord;

[mapView addAnnotation:ann];

Answer 2

乍一看：

  ann.title = @"%@", [stream valueForKey:@"TheTime"];

应该是

  ann.title = [NSString stringWithFormat: @"%@", [stream valueForKey:@"TheTime"]];

我猜