ios - 运行代码的iOS CLLocation顺序

我已经设法使用GLGeocoder geocodeAddressString获得2个城市的坐标

从名称中检索出这两个城市坐标后，我想计算它们之间的距离。但是我面临的问题是CLLocationDistance在geocodeAddressString之前运行。

如何确保仅在城市位置后才计算距离？

请在下面查看我的代码：

__block CLLocation *depLocation;
__block CLLocation *arrLocation;

CLGeocoder *geocoder = [[CLGeocoder alloc] init];
[geocoder geocodeAddressString:@"Birmingham" completionHandler:^(NSArray* placemarks, NSError* error){
    for (CLPlacemark* aPlacemark in placemarks)
    {

        depLocation = [[CLLocation alloc]
                       initWithLatitude:aPlacemark.location.coordinate.latitude
                       longitude:aPlacemark.location.coordinate.longitude];

    }
}];

CLGeocoder *geocoder2 = [[CLGeocoder alloc] init];
[geocoder2 geocodeAddressString:@"Amritsar" completionHandler:^(NSArray* placemarks2, NSError* error){
    for (CLPlacemark* aPlacemark2 in placemarks2)
    {

        arrLocation = [[CLLocation alloc]
                       initWithLatitude:aPlacemark2.location.coordinate.latitude
                       longitude:aPlacemark2.location.coordinate.longitude];

    }
}];

CLLocationDistance distanceXYZ = [depLocation distanceFromLocation:arrLocation];
NSString *distanceLabel = [NSString stringWithFormat:@"Distance to point %4.0f m.", distanceXYZ];

最佳答案

简单的答案是嵌套所有的完成块。复制所有geoCoder2内容并将其放入geocoder完成块中，然后将distanceXYZ和distanceLabel复制到geocoder2的完成块中