CTParagraphStyle+CopyTextTab.swift

// NG
func copyTextTab(_ style: CTParagraphStyle) -> [CTTextTab] {
    var tabStops: CFArray!
    guard CTParagraphStyleGetValueForSpecifier(style, .tabStops, MemoryLayout<CFArray>.size, &tabStops) else {
        return []
    }
    return (tabStops as NSArray)
        .filter({ (tab) -> Bool in CFGetTypeID(tab as CFTypeRef) == CTTextTabGetTypeID() })
        .map({ (it) -> CTTextTab in
            let tab = it as! CTTextTab
            let alignment = CTTextTabGetAlignment(tab)
            let location = CTTextTabGetLocation(tab)
            let options = CTTextTabGetOptions(tab)
            return CTTextTabCreate(alignment, location, options)
        })
    }
}

// OK
func copyTextTab(_ style: CTParagraphStyle) -> [CTTextTab] {
    let storage = UnsafeMutablePointer<CFArray>.allocate(capacity: MemoryLayout<CFArray>.size)
    guard CTParagraphStyleGetValueForSpecifier(style, .tabStops, MemoryLayout<CFArray>.size, storage) else {
        return []
    }
    guard CFGetTypeID(storage.pointee) == CFArrayGetTypeID() else {
        return []
    }
    let result = (storage.pointee as NSArray)
                .filter({ (it) -> Bool in CFGetTypeID(it as CFTypeRef!) == CTTextTabGetTypeID() })
                .map({ (it) -> CTTextTab in
                    let tab = it as! CTTextTab
                    return CTTextTabCreate(CTTextTabGetAlignment(tab), CTTextTabGetLocation(tab), CTTextTabGetOptions(tab))
                })
    storage.deallocate(capacity: MemoryLayout<CFArray>.size)

    return result
}