从Parse.com查询数据,遍历,将某些部分添加到NSObject,并将该对象添加到对象数组中

好了,伙计们,最后我想好了如何在一个实际可行的街区里做到这一点:

- (void)queryForAllPostsNearLocation:(CLLocation *)currentLocation withNearbyDistance:(CLLocationAccuracy)nearbyDistance {
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setBool:1 forKey:@"Users"];
    PFQuery *query = [PFQuery queryWithClassName:@"_User"];
    // If no objects are loaded in memory, we look to the cache first to fill the table
    // and then subsequently do a query against the network.
    if (query.countObjects == 0) {
        query.cachePolicy = kPFCachePolicyCacheThenNetwork;
    }

    // Create a PFGeoPoint using the current location (to use in our query)
    PFGeoPoint *userLocation =
    [PFGeoPoint geoPointWithLatitude:[Global shared].LastLocation.latitude longitude:[Global shared].LastLocation.longitude];

    // Create a PFQuery asking for all wall posts 1km of the user
    [query whereKey:@"CurrentCityCoordinates" nearGeoPoint:userLocation withinKilometers:10];
    // Include the associated PFUser objects in the returned data
    [query includeKey:@"objectId"];
    //Run the query in background with completion block
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
    if (error) { // The query failed
        NSLog(@"Error in geo query!");
    } else { // The query is successful
        defaultPeople = [[NSMutableArray alloc] init];
        // 1. Find new posts (those that we did not already have)
        // In this array we'll store the posts returned by the query
        NSMutableArray *people = [[NSMutableArray alloc] initWithCapacity:100];
        // Loop through all returned PFObjects
        for (PFObject *object in objects) {
            // Create an object of type Person with the PFObject
            Person *p = [[Person alloc] init];
            NSString *userID = object.objectId;
            p.objectId = userID;

            NSString *first = [object objectForKey:@"FirstName"];
            p.name = first;

            NSString *city = [object objectForKey:@"CurrentCity"];
            p.location = city;

            NSString *age = [object objectForKey:@"Age"];
            p.age = age;

            NSString *gender = [object objectForKey:@"Gender"];
            p.gender = gender;

            NSString *tagline = [object objectForKey:@"Tagline"];
            p.tagline = tagline;

            UIImage *img = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@",[object objectForKey:@"PictureURL"]]]]];
            p.image = img;
            if (![p.objectId isEqualToString:myID] && ![p.gender isEqualToString:myGender] && ![people containsObject:p]) {
                [people addObject:p];
                NSLog(@"Person: %@",p);
            }
        }
        [defaultPeople addObjectsFromArray:people];
        [[Global shared] setDefaultPeople:defaultPeople];
        NSLog(@"Default People: %@",[Global shared].defaultPeople);
        NSLog(@"Success. Retrieved %lu objects.", (unsigned long)[Global shared].defaultPeople.count);
        if (defaultPeople.count == 0) {
            [defaults setBool:0 forKey:@"Users"];
        } else {
            [defaults setBool:1 forKey:@"Users"];
            }
        }
    }];
}

底部的BOOL返回是为了让控制器知道是否在提示时切换视图控制器。如果按下开关控制器切换开关,则仅在BOOL=1(即该区域有人)时切换。

谢谢你所有的帮助。认真地

[self.people addObject:p]在后台线程中发生,因此“return self.peoples”在self.pepeople更新之前发生。这就是为什么它总是返回零。

代替[query findObjectsInBackground],您可以 NSArray*objects=[query findObjects]

您需要返回块内的人,否则它将在完成查找对象之前命中return语句。它与块异步地查找它们。

另一种选择是摆脱障碍,并做到:

NSArray *array = [query findObjects];

for (PFObject *object in array) {
                        NSString *userID = object.objectId;
                        NSString *first = [object objectForKey:@"FirstName"];
                        NSString *city = [object objectForKey:@"CurrentCity"];
                        NSUInteger age = (int)[object objectForKey:@"Age"];
                        NSString *gender = [object objectForKey:@"Gender"];
                        NSString *tagline = [object objectForKey:@"Tagline"];

                        Person *p = [[Person alloc] 
                                            initWithName:first
                                                   image:[UIImage imageWithData:
                                                         [NSData dataWithContentsOfURL:                                                                                            
                                                         [NSURL URLWithString:
                                                         [object objectForKey:@"PictureURL"]]]]
                                                 age:age
                                              gender:gender
                                            location:city
                                             tagline:tagline
                                            objectId:userID];
                [self.people addObject:p];

}

return self.people;