NSPredicate 根据 UUID 过滤 beacon，major 和 minor 引发异常

Question

我有一个包含 CLBeacon 集合的 beacons 数组，我只想获取与 NSPredicate 中给定的 uuid、主要和次要匹配的信标。下面是对象 C 中的代码，它由于谓词中的 UUID 而生成异常。如果我从查询中删除 uuidPredicate，代码工作正常。

 - (void)locationManager:(CLLocationManager *)manager didRangeBeacons:(NSArray<CLBeacon *> *)beacons inRegion:(CLBeaconRegion *)region{

        NSPredicate *uuidPredicate = [NSPredicate predicateWithFormat:@"uuid.UUIDString == [c] %@", @"03672ce6-9272-48ea-ba54-0bf679217980"];
       //NSPredicate *uuidPredicate = [NSPredicate predicateWithFormat:@"uuid == %@", @"03672ce6-9272-48ea-ba54-0bf679217980"];
        NSPredicate *majorPredicate = [NSPredicate predicateWithFormat:@"major = %ld", 1];
        NSPredicate *minorPredicate = [NSPredicate predicateWithFormat:@"minor = %ld", 3];

        NSPredicate *compoundPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:@[uuidPredicate, majorPredicate, minorPredicate]];

        NSArray *pointABeacon = [beacons filteredArrayUsingPredicate:compoundPredicate];   

    }

信标数组类似于

beacons (
    "CLBeacon (uuid:03672CE6-9272-48EA-BA54-0BF679217980, major:1, minor:1, proximity:1 +/- 0.07m, rssi:-61)",
    "CLBeacon (uuid:03672CE6-9272-48EA-BA54-0BF679217980, major:1, minor:2, proximity:1 +/- 0.07m, rssi:-62)",
    "CLBeacon (uuid:03672CE6-9272-48EA-BA54-0BF679217981, major:1, minor:3, proximity:2 +/- 1.64m, rssi:-53)"
)

例外是

*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[< CLBeacon 0x1c401c410 > valueForUndefinedKey:]: this class is not key value coding-compliant for the key uuid.'

如何过滤uuid,major,minor三个参数的数组？

Answer 1

错误很明显： CLBeacon 对象没有名为 uuid.

的属性

当您打印 CLBeacon 对象时，您可能会看到 "uuid"，但这不是属性的真实名称，而是 proximityUUID

所以：

NSPredicate *uuidPredicate = [NSPredicate predicateWithFormat:@"uuid.UUIDString == [c] %@", @"03672ce6-9272-48ea-ba54-0bf679217980"];

应该是：

NSPredicate *uuidPredicate = [NSPredicate predicateWithFormat:@"proximityUUID.UUIDString == [c] %@", @"03672ce6-9272-48ea-ba54-0bf679217980"];

NSPredicate 根据 UUID 过滤 beacon，major 和 minor 引发异常

NSPredicate to filter beacon according to UUID, major and minor raising exception

nspredicate

ibeacon

nscompoundpredicate

clbeacon