Find Closest Beacon in every second by using RSSI in Objective-C

Question

In Stack Overflow, I've seen answer to find closest beacon (Swift find closest Beacon by rssi).

Here I tried with accuracy to find closest in Objective-C. My app finds beacon in every sec that time accuracy is not working finding closest properly. As he said RSSI will update in every 1 sec. So I'd like to filter closest beacon using RSSI. I converted your Swift code into Objective-C but it's not working fine.

Here is Swift code:

//Swift code
var closestBeacon: CLBeacon? = nil
for beacon in beacons {
    if beacon.rssi < 0 && closestBeacon != nil && beacon.rssi > closestBeacon!.rssi {
        closestBeacon = beacon as? CLBeacon
    }
}

Here is Objective-C code I converted not working:

CLBeacon *closest = nil;

for (CLBeacon *beacon in beacons) {

    if (beacon.rssi < 0 &&  closest != nil && beacon.rssi > closest.rssi) {

        closest = beacon;

    }
}

Here please make me perfect where I'm doing wrong.

You need to set assign a value to `closest` at some point before your loop or it will always be `nil` and the `if` will never be true — Paulw11, Jun 29 '19 at 08:01
@P4yam, I've approved your edit, but see my subsequent edit for how to do proper code formatting. — Cœur, Jun 29 '19 at 08:29
I think that you could use `max(by:)` to find the Beacon with the max value, and the compare it with yours saved beacon if exists to set it. — Larme, Jun 29 '19 at 11:07

davidgyoung · Answer 1 · 2019-06-29T16:56:24.047

0

There is a bug in both versions of code as @paulw11 suggests. Since I wrote that bug in response to another question here is a fix:

Swift

var closestBeacon: CLBeacon? = nil
for beacon in beacons {
    if closestBeacon == nil || beacon.rssi < 0 && beacon.rssi > closestBeacon!.rssi {
        closestBeacon = beacon as? CLBeacon
    }
}

Objective-C

CLBeacon *closestBeacon = nil;

for (CLBeacon *beacon in beacons) {

    if (closestBeacon == nil || beacon.rssi < 0 && beacon.rssi > closest.rssi) {

        closestBeacon = beacon;

    }
}

I fixed the bug in the original post, too.

edited Jun 29 '19 at 16:56

answered Jun 29 '19 at 15:29

davidgyoung

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let me try and comeback to you. Here in your answer closestBeacon is beacon? or need to take another CLBeacon property. Otherwise compiler throws error. – Eshwar Jun 29 '19 at 16:41
I edited the answer. To be consistent with the swift version, I have named the variable closestBeacon – davidgyoung Jun 29 '19 at 16:56

Find Closest Beacon in every second by using RSSI in Objective-C

1 Answers1