加快从谷歌地理编码addAnnotations？

问题描述：

我在我的应用程序下面的code它增加了一些注释，以通过谷歌的地理编码一个图形页面：

I have the following code in my app which adds a number of Annotations to a mapview via Google geocoding:

for (PlaceObject *info in mapLocations) {

    NSString * addressOne = info.addressOne;
    NSString * name = info.name;

    NSString * address = [addressOne stringByAppendingString:@",London"];

    NSError * error;

    NSString *urlString = [NSString stringWithFormat:@"http://maps.google.com/maps/geo?q=%@&output=csv", [address stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

    NSString *locationString = [NSString stringWithContentsOfURL:[NSURL URLWithString:urlString ] encoding:NSASCIIStringEncoding error:&error];
    NSArray *listItems = [locationString componentsSeparatedByString:@","];

    double latitude = 0.0;
    double longitude = 0.0;

    if([listItems count] >= 4 && [[listItems objectAtIndex:0] isEqualToString:@"200"]) {
        latitude = [[listItems objectAtIndex:2] doubleValue];
        longitude = [[listItems objectAtIndex:3] doubleValue];

    } else {
        //Error handling

    }        

    CLLocationCoordinate2D coordinate;
    coordinate.latitude = latitude;
    coordinate.longitude = longitude;
    MyLocation *annotation = [[[MyLocation alloc] initWithName:name address:address coordinate:coordinate] autorelease];
    [mapViewLink addAnnotation:annotation];

}

这个工作，但它需要较长的时间用于视图显示为似乎要等到该阵列中的所有对象已通过环（有大约80）。

This works, however it takes a long time for the view to appear as it seems to wait until all objects in the array have been looped through (there are about 80).

有没有什么办法，使视图负荷，然后为他们创建要添加的销？

Is there any way to make the view load and then for the pins to be added as they are created ?

答

这个怎么样：

for (PlaceObject *info in mapLocations) {

    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_async(queue, ^{

        // GET ANNOTATION INFOS
        NSString * addressOne = info.addressOne;
        NSString * name = info.name;

        NSString * address = [addressOne stringByAppendingString:@",London"];

        NSError * error;

        NSString *urlString = [NSString stringWithFormat:@"http://maps.google.com/maps/geo?q=%@&output=csv", [address stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

        NSString *locationString = [NSString stringWithContentsOfURL:[NSURL URLWithString:urlString ] encoding:NSASCIIStringEncoding error:&error];
        NSArray *listItems = [locationString componentsSeparatedByString:@","];

        double latitude = 0.0;
        double longitude = 0.0;

        if([listItems count] >= 4 && [[listItems objectAtIndex:0] isEqualToString:@"200"]) {
            latitude = [[listItems objectAtIndex:2] doubleValue];
            longitude = [[listItems objectAtIndex:3] doubleValue];

        } else {
            //Error handling

        }        

        CLLocationCoordinate2D coordinate;
        coordinate.latitude = latitude;
        coordinate.longitude = longitude;
        MyLocation *annotation = [[[MyLocation alloc] initWithName:name address:address coordinate:coordinate] autorelease]; 

        dispatch_sync(dispatch_get_main_queue(), ^{

            // ADD ANNOTATION
            [mapViewLink addAnnotation:annotation];

        });

    });
}

但请考虑要仔细检查这一code。有definitily事情你应该做的关于保持线程安全，避免 EXC_BAD_ACCESS 。

加快从谷歌地理编码addAnnotations？

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