How to check bitfields (SCNetworkReachabilityFlags in particular) for flags in Swift?

bit-fields, bitmask, ios, swift

Solution

That error is actually complaining not about the arguments of your flags-check, but about the return value. An `if` statement expects a boolean (or at least something conforming to `Logical`), but the `&` operator for two `Int` values returns an `Int`. You just need a comparison in your `if` statement:

let flags = kSCNetworkReachabilityFlagsReachable
if 0 != flags & kSCNetworkReachabilityFlagsReachable {
    println("flags contains kSCNetworkReachabilityFlagsReachable")
}

Since `SCNetworkReachabilityFlags` and the constants are (strangely) of different types, you'll need to do some casting to make the comparison work:

let reachabilityFlags:SCNetworkReachabilityFlags = SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsReachable)
if 0 != reachabilityFlags & SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsReachable) {
    println("reachabilityFlags contains kSCNetworkReachabilityFlagsReachable")
}

Problem

I have a `SCNetworkReachabilityFlags` variable and want to check it for particular values, e.g. if the network is reachable via WWAN. The `SCNetworkReachabilityFlags` type is a `typealias` for `UInt32` and the various options are defined as `Int` variables. Using Objective-C you could do the following: ``` if (flags & kSCNetworkReachabilityFlagsIsWWAN) { // do stuff } ``` In Swift if I try this: ``` if reachabilityFlags & kSCNetworkReachabilityFlagsIsWWAN { // do stuff } ``` you get a compiler error: `Could not find an overload for '&' that accepts the supplied arguments`. I've read some other questions where the bitfield options where defined as a `RawOptionSet` struct. This hasn't been done in `SCNetworkReachability`. How to you check for flags in Swift?

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