How to detect Network Signal Strength in iOS Reachability
My original thought was to time the download of a file, and see how long it takes:
@interface ViewController ()
@property (nonatomic) CFAbsoluteTime startTime;
@property (nonatomic) CFAbsoluteTime stopTime;
@property (nonatomic) long long bytesReceived;
@property (nonatomic, copy) void (^speedTestCompletionHandler)(CGFloat megabytesPerSecond, NSError *error);
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self testDownloadSpeedWithTimout:5.0 completionHandler:^(CGFloat megabytesPerSecond, NSError *error) {
NSLog(@"%0.1f; error = %@", megabytesPerSecond, error);
}];
}
/// Test speed of download
///
/// Test the speed of a connection by downloading some predetermined resource. Alternatively, you could add the
/// URL of what to use for testing the connection as a parameter to this method.
///
/// @param timeout The maximum amount of time for the request.
/// @param completionHandler The block to be called when the request finishes (or times out).
/// The error parameter to this closure indicates whether there was an error downloading
/// the resource (other than timeout).
///
/// @note Note, the timeout parameter doesn't have to be enough to download the entire
/// resource, but rather just sufficiently long enough to measure the speed of the download.
- (void)testDownloadSpeedWithTimout:(NSTimeInterval)timeout completionHandler:(nonnull void (^)(CGFloat megabytesPerSecond, NSError * _Nullable error))completionHandler {
NSURL *url = [NSURL URLWithString:@"http://insert.your.site.here/yourfile"];
self.startTime = CFAbsoluteTimeGetCurrent();
self.stopTime = self.startTime;
self.bytesReceived = 0;
self.speedTestCompletionHandler = completionHandler;
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration ephemeralSessionConfiguration];
configuration.timeoutIntervalForResource = timeout;
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
[[session dataTaskWithURL:url] resume];
}
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {
self.bytesReceived += [data length];
self.stopTime = CFAbsoluteTimeGetCurrent();
}
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {
CFAbsoluteTime elapsed = self.stopTime - self.startTime;
CGFloat speed = elapsed != 0 ? self.bytesReceived / (CFAbsoluteTimeGetCurrent() - self.startTime) / 1024.0 / 1024.0 : -1;
// treat timeout as no error (as we're testing speed, not worried about whether we got entire resource or not
if (error == nil || ([error.domain isEqualToString:NSURLErrorDomain] && error.code == NSURLErrorTimedOut)) {
self.speedTestCompletionHandler(speed, nil);
} else {
self.speedTestCompletionHandler(speed, error);
}
}
@end
Note, this measures the speed including the latency of starting the connection. You could alternatively initialize startTime in didReceiveResponse, if you wanted to factor out that initial latency.
Having done that, in retrospect, I don't like spending time or bandwidth downloading something that has no practical benefit to the app. So, as an alternative, I might suggest a far more pragmatic approach: Why don't you just try to open a MKMapView and see how long it takes to finish downloading the map? If it fails or if it takes more than a certain amount of time, then switch to your offline map. Again, there is quite a bit of variability here (not only because network bandwidth and latency, but also because some map images appear to be cached), so make sure to set a kMaximumElapsedTime to be large enough to handle all the reasonable permutations of a successful connection (i.e., don't be too aggressive in using a low value).
To do this, just make sure to set your view controller to be the delegate of the MKMapView. And then you can do:
@interface ViewController ()
@property (nonatomic, strong) NSDate *startDate;
@end
static CGFloat const kMaximumElapsedTime = 5.0;
@implementation ViewController
// insert the rest of your implementation here
#pragma mark - MKMapViewDelegate methods
- (void)mapViewWillStartLoadingMap:(MKMapView *)mapView {
NSDate *localStartDate = [NSDate date];
self.startDate = localStartDate;
double delayInSeconds = kMaximumElapsedTime;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
// Check to see if either:
// (a) start date property is not nil (because if it is, we
// finished map download); and
// (b) start date property is the same as the value we set
// above, as it's possible this map download is done, but
// we're already in the process of downloading the next
// map.
if (self.startDate && self.startDate == localStartDate)
{
[[[UIAlertView alloc] initWithTitle:nil
message:[NSString stringWithFormat:@"Map timed out after %.1f", delayInSeconds]
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil] show];
}
});
}
- (void)mapViewDidFailLoadingMap:(MKMapView *)mapView withError:(NSError *)error {
self.startDate = nil;
[[[UIAlertView alloc] initWithTitle:nil
message:@"Online map failed"
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil] show];
}
- (void)mapViewDidFinishLoadingMap:(MKMapView *)mapView
{
NSTimeInterval elapsed = [[NSDate date] timeIntervalSinceDate:self.startDate];
self.startDate = nil;
self.statusLabel.text = [NSString stringWithFormat:@"%.1f seconds", elapsed];
}
Reachability and signal strength
The behavior that you are describing is exactly how I would expect the Reachability API to behave. Its basically a way to simply know if your device is connected over WiFi, cellular or has no connection at all. It gives no indication of the signal strength or the quality of the network connection.
Detecting Network Connectivity Changes using Reachability, NSNotification and Network Link Conditioner in Swift
You must create a Reachability object before you can receive notifications from it. Also, be sure to call the startNotifier() method on the Reachability object you create. This would be an example of how to do so inside of your application delegate:
class AppDelegate: UIResponder, UIApplicationDelegate
{
private var reachability:Reachability!;
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool
{
NSNotificationCenter.defaultCenter().addObserver(self, selector:"checkForReachability:", name: kReachabilityChangedNotification, object: nil);
self.reachability = Reachability.reachabilityForInternetConnection();
self.reachability.startNotifier();
}
@objc func checkForReachability(notification:NSNotification)
{
// Remove the next two lines of code. You cannot instantiate the object
// you want to receive notifications from inside of the notification
// handler that is meant for the notifications it emits.
//var networkReachability = Reachability.reachabilityForInternetConnection()
//networkReachability.startNotifier()
let networkReachability = notification.object as Reachability;
var remoteHostStatus = networkReachability.currentReachabilityStatus()
if (remoteHostStatus.value == NotReachable.value)
{
println("Not Reachable")
}
else if (remoteHostStatus.value == ReachableViaWiFi.value)
{
println("Reachable via Wifi")
}
else
{
println("Reachable")
}
}
}
I recommend you take a look at the documentation for NSNotificationCenter and NSNotification. That way you'll be more familiar with how to work with notifications next time something like this comes up.
Swift 3
NotificationCenter.default.addObserver(self, selector:Selector(("checkForReachability:")), name: NSNotification.Name.reachabilityChanged, object: nil)
let reachability: Reachability = Reachability.forInternetConnection()
reachability.startNotifier()
How to check if device is having poor internet connection in swift
I have founded solution and adding it here.
Simply create class and paste it and use it where you want.
protocol NetworkSpeedProviderDelegate: class {
func callWhileSpeedChange(networkStatus: NetworkStatus)
}
public enum NetworkStatus :String
{case poor; case good; case disConnected}
class NetworkSpeedTest: UIViewController {
weak var delegate: NetworkSpeedProviderDelegate?
var startTime = CFAbsoluteTime()
var stopTime = CFAbsoluteTime()
var bytesReceived: CGFloat = 0
var testURL:String?
var speedTestCompletionHandler: ((_ megabytesPerSecond: CGFloat, _ error: Error?) -> Void)? = nil
var timerForSpeedTest:Timer?
func networkSpeedTestStart(UrlForTestSpeed:String!){
testURL = UrlForTestSpeed
timerForSpeedTest = Timer.scheduledTimer(timeInterval: 60.0, target: self, selector: #selector(testForSpeed), userInfo: nil, repeats: true)
}
func networkSpeedTestStop(){
timerForSpeedTest?.invalidate()
}
@objc func testForSpeed()
{
testDownloadSpeed(withTimout: 2.0, completionHandler: {(_ megabytesPerSecond: CGFloat, _ error: Error?) -> Void in
print("%0.1f; KbPerSec = \(megabytesPerSecond)")
if (error as NSError?)?.code == -1009
{
self.delegate?.callWhileSpeedChange(networkStatus: .disConnected)
}
else if megabytesPerSecond == -1.0
{
self.delegate?.callWhileSpeedChange(networkStatus: .poor)
}
else
{
self.delegate?.callWhileSpeedChange(networkStatus: .good)
}
})
}
}
extension NetworkSpeedTest: URLSessionDataDelegate, URLSessionDelegate {
func testDownloadSpeed(withTimout timeout: TimeInterval, completionHandler: @escaping (_ megabytesPerSecond: CGFloat, _ error: Error?) -> Void) {
// you set any relevant string with any file
let urlForSpeedTest = URL(string: testURL!)
startTime = CFAbsoluteTimeGetCurrent()
stopTime = startTime
bytesReceived = 0
speedTestCompletionHandler = completionHandler
let configuration = URLSessionConfiguration.ephemeral
configuration.timeoutIntervalForResource = timeout
let session = URLSession(configuration: configuration, delegate: self, delegateQueue: nil)
guard let checkedUrl = urlForSpeedTest else { return }
session.dataTask(with: checkedUrl).resume()
}
func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
bytesReceived += CGFloat(data.count)
stopTime = CFAbsoluteTimeGetCurrent()
}
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
let elapsed = (stopTime - startTime) //as? CFAbsoluteTime
let speed: CGFloat = elapsed != 0 ? bytesReceived / (CGFloat(CFAbsoluteTimeGetCurrent() - startTime)) / 1024.0 : -1.0
// treat timeout as no error (as we're testing speed, not worried about whether we got entire resource or not
if error == nil || ((((error as NSError?)?.domain) == NSURLErrorDomain) && (error as NSError?)?.code == NSURLErrorTimedOut) {
speedTestCompletionHandler?(speed, nil)
}
else {
speedTestCompletionHandler?(speed, error)
}
}
}
After That how to use it.So implement delegate and use it.
class ViewController: UIViewController, NetworkSpeedProviderDelegate {
func callWhileSpeedChange(networkStatus: NetworkStatus) {
switch networkStatus {
case .poor:
break
case .good:
break
case .disConnected:
break
}
}
let test = NetworkSpeedTest()
override func viewDidLoad() {
super.viewDidLoad()
test.delegate = self
test.networkSpeedTestStop()
test.networkSpeedTestStart(UrlForTestSpeed: "Paste Your Any Working URL ")
// Do any additional setup after loading the view.
}
}
Accurately reading of iPhone signal strength
Ok I think I have the correct solution now, which was a bit simpler in the end.
The issue with the CTGetSignalStrength() method is that it works normally, but if you remove a sim, it reports the last signal before the removal. I found another method in the same framework called CTSIMSupportGetSIMStatus(), also undocumented, which can tell you if a SIM is currently connected. Using both as follows should confirm the current network signal.
First declare the methods:
NSString * CTSIMSupportGetSIMStatus();
int CTGetSignalStrength();
Then check connectivity to cell network like so:
NSString *status = CTSIMSupportGetSIMStatus();
int signalstrength = CTGetSignalStrength();
BOOL connected = ( [status isEqualToString: @"kCTSIMSupportSIMStatusReady"] && signalstrength > 0 );
How to detect at realtime the increase/decrease of cellular signal power in iOS
To detect cellular signal power I use CTRadioAccessTechnologyDidChangeNotification.
You can try this code :
import CoreTelephony
private var info: CTTelephonyNetworkInfo!
func createObserver() {
self.info = CTTelephonyNetworkInfo();
NSNotificationCenter.defaultCenter().addObserver(self, selector: "currentAccessTechnologyDidChange",
name: CTRadioAccessTechnologyDidChangeNotification, object: self.observerObject)
}
func currentAccessTechnologyDidChange() {
if let currentAccess = self.info.currentRadioAccessTechnology {
switch currentAccess {
case CTRadioAccessTechnologyGPRS:
print("GPRS")
case CTRadioAccessTechnologyEdge:
print("EDGE")
case CTRadioAccessTechnologyWCDMA:
print("WCDMA")
case CTRadioAccessTechnologyHSDPA:
print("HSDPA")
case CTRadioAccessTechnologyHSUPA:
print("HSUPA")
case CTRadioAccessTechnologyCDMA1x:
print("CDMA1x")
case CTRadioAccessTechnologyCDMAEVDORev0:
print("CDMAEVDORev0")
case CTRadioAccessTechnologyCDMAEVDORevA:
print("CDMAEVDORevA")
case CTRadioAccessTechnologyCDMAEVDORevB:
print("CDMAEVDORevB")
case CTRadioAccessTechnologyeHRPD:
print("HRPD")
case CTRadioAccessTechnologyLTE:
print("LTE")
default:
print("DEF")
}
} else {
print("Current Access technology is NIL")
}
}
I've tested it on my iphone by turning on/off airplane mode and I've noticed that sometimes I have to wait a bit more time for notification. So maybe the better way in your case will be just called info.currentRadioAccessTechnology and get the result when you need it. Of course, remember to remove observer when you don't need it anymore.
Apple documentation about this :
currentRadioAccessTechnology
Discussion:
The current radio access technology the device is registered with. May beNULLif the device is not registered on any network.
Additionaly, I do some research and I found an interesting answer which might help you.
Simple Obj-C version :
#import
CTTelephonyNetworkInfo *ctInfo = [CTTelephonyNetworkInfo new];
[[NSNotificationCenter defaultCenter] addObserverForName:CTRadioAccessTechnologyDidChangeNotification object:nil queue:nil usingBlock:^(NSNotification *note) {
NSLog(@"current access radio access did change to : %@", ctInfo.currentRadioAccessTechnology);
}];
Check for internet connection with Swift
To solve the 4G issue mentioned in the comments I have used @AshleyMills reachability implementation as a reference and rewritten Reachability for Swift 3.1:
updated: Xcode 10.1 • Swift 4 or later
Reachability.swift file
import Foundation
import SystemConfiguration
class Reachability {
var hostname: String?
var isRunning = false
var isReachableOnWWAN: Bool
var reachability: SCNetworkReachability?
var reachabilityFlags = SCNetworkReachabilityFlags()
let reachabilitySerialQueue = DispatchQueue(label: "ReachabilityQueue")
init(hostname: String) throws {
guard let reachability = SCNetworkReachabilityCreateWithName(nil, hostname) else {
throw Network.Error.failedToCreateWith(hostname)
}
self.reachability = reachability
self.hostname = hostname
isReachableOnWWAN = true
try start()
}
init() throws {
var zeroAddress = sockaddr_in()
zeroAddress.sin_len = UInt8(MemoryLayout.size)
zeroAddress.sin_family = sa_family_t(AF_INET)
guard let reachability = withUnsafePointer(to: &zeroAddress, {
$0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
SCNetworkReachabilityCreateWithAddress(nil, $0)
}
}) else {
throw Network.Error.failedToInitializeWith(zeroAddress)
}
self.reachability = reachability
isReachableOnWWAN = true
try start()
}
var status: Network.Status {
return !isConnectedToNetwork ? .unreachable :
isReachableViaWiFi ? .wifi :
isRunningOnDevice ? .wwan : .unreachable
}
var isRunningOnDevice: Bool = {
#if targetEnvironment(simulator)
return false
#else
return true
#endif
}()
deinit { stop() }
}
extension Reachability {
func start() throws {
guard let reachability = reachability, !isRunning else { return }
var context = SCNetworkReachabilityContext(version: 0, info: nil, retain: nil, release: nil, copyDescription: nil)
context.info = Unmanaged.passUnretained(self).toOpaque()
guard SCNetworkReachabilitySetCallback(reachability, callout, &context) else { stop()
throw Network.Error.failedToSetCallout
}
guard SCNetworkReachabilitySetDispatchQueue(reachability, reachabilitySerialQueue) else { stop()
throw Network.Error.failedToSetDispatchQueue
}
reachabilitySerialQueue.async { self.flagsChanged() }
isRunning = true
}
func stop() {
defer { isRunning = false }
guard let reachability = reachability else { return }
SCNetworkReachabilitySetCallback(reachability, nil, nil)
SCNetworkReachabilitySetDispatchQueue(reachability, nil)
self.reachability = nil
}
var isConnectedToNetwork: Bool {
return isReachable &&
!isConnectionRequiredAndTransientConnection &&
!(isRunningOnDevice && isWWAN && !isReachableOnWWAN)
}
var isReachableViaWiFi: Bool {
return isReachable && isRunningOnDevice && !isWWAN
}
/// Flags that indicate the reachability of a network node name or address, including whether a connection is required, and whether some user intervention might be required when establishing a connection.
var flags: SCNetworkReachabilityFlags? {
guard let reachability = reachability else { return nil }
var flags = SCNetworkReachabilityFlags()
return withUnsafeMutablePointer(to: &flags) {
SCNetworkReachabilityGetFlags(reachability, UnsafeMutablePointer($0))
} ? flags : nil
}
/// compares the current flags with the previous flags and if changed posts a flagsChanged notification
func flagsChanged() {
guard let flags = flags, flags != reachabilityFlags else { return }
reachabilityFlags = flags
NotificationCenter.default.post(name: .flagsChanged, object: self)
}
/// The specified node name or address can be reached via a transient connection, such as PPP.
var transientConnection: Bool { return flags?.contains(.transientConnection) == true }
/// The specified node name or address can be reached using the current network configuration.
var isReachable: Bool { return flags?.contains(.reachable) == true }
/// The specified node name or address can be reached using the current network configuration, but a connection must first be established. If this flag is set, the kSCNetworkReachabilityFlagsConnectionOnTraffic flag, kSCNetworkReachabilityFlagsConnectionOnDemand flag, or kSCNetworkReachabilityFlagsIsWWAN flag is also typically set to indicate the type of connection required. If the user must manually make the connection, the kSCNetworkReachabilityFlagsInterventionRequired flag is also set.
var connectionRequired: Bool { return flags?.contains(.connectionRequired) == true }
/// The specified node name or address can be reached using the current network configuration, but a connection must first be established. Any traffic directed to the specified name or address will initiate the connection.
var connectionOnTraffic: Bool { return flags?.contains(.connectionOnTraffic) == true }
/// The specified node name or address can be reached using the current network configuration, but a connection must first be established.
var interventionRequired: Bool { return flags?.contains(.interventionRequired) == true }
/// The specified node name or address can be reached using the current network configuration, but a connection must first be established. The connection will be established "On Demand" by the CFSocketStream programming interface (see CFStream Socket Additions for information on this). Other functions will not establish the connection.
var connectionOnDemand: Bool { return flags?.contains(.connectionOnDemand) == true }
/// The specified node name or address is one that is associated with a network interface on the current system.
var isLocalAddress: Bool { return flags?.contains(.isLocalAddress) == true }
/// Network traffic to the specified node name or address will not go through a gateway, but is routed directly to one of the interfaces in the system.
var isDirect: Bool { return flags?.contains(.isDirect) == true }
/// The specified node name or address can be reached via a cellular connection, such as EDGE or GPRS.
var isWWAN: Bool { return flags?.contains(.isWWAN) == true }
/// The specified node name or address can be reached using the current network configuration, but a connection must first be established. If this flag is set
/// The specified node name or address can be reached via a transient connection, such as PPP.
var isConnectionRequiredAndTransientConnection: Bool {
return (flags?.intersection([.connectionRequired, .transientConnection]) == [.connectionRequired, .transientConnection]) == true
}
}
func callout(reachability: SCNetworkReachability, flags: SCNetworkReachabilityFlags, info: UnsafeMutableRawPointer?) {
guard let info = info else { return }
DispatchQueue.main.async {
Unmanaged
.fromOpaque(info)
.takeUnretainedValue()
.flagsChanged()
}
}
extension Notification.Name {
static let flagsChanged = Notification.Name("FlagsChanged")
}
struct Network {
static var reachability: Reachability!
enum Status: String {
case unreachable, wifi, wwan
}
enum Error: Swift.Error {
case failedToSetCallout
case failedToSetDispatchQueue
case failedToCreateWith(String)
case failedToInitializeWith(sockaddr_in)
}
}
Usage
Initialize it in your AppDelegate.swift didFinishLaunchingWithOptions method and handle any errors that might occur:
import UIKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
do {
try Network.reachability = Reachability(hostname: "www.google.com")
}
catch {
switch error as? Network.Error {
case let .failedToCreateWith(hostname)?:
print("Network error:\nFailed to create reachability object With host named:", hostname)
case let .failedToInitializeWith(address)?:
print("Network error:\nFailed to initialize reachability object With address:", address)
case .failedToSetCallout?:
print("Network error:\nFailed to set callout")
case .failedToSetDispatchQueue?:
print("Network error:\nFailed to set DispatchQueue")
case .none:
print(error)
}
}
return true
}
}
And a view controller sample:
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
NotificationCenter.default
.addObserver(self,
selector: #selector(statusManager),
name: .flagsChanged,
object: nil)
updateUserInterface()
}
func updateUserInterface() {
switch Network.reachability.status {
case .unreachable:
view.backgroundColor = .red
case .wwan:
view.backgroundColor = .yellow
case .wifi:
view.backgroundColor = .green
}
print("Reachability Summary")
print("Status:", Network.reachability.status)
print("HostName:", Network.reachability.hostname ?? "nil")
print("Reachable:", Network.reachability.isReachable)
print("Wifi:", Network.reachability.isReachableViaWiFi)
}
@objc func statusManager(_ notification: Notification) {
updateUserInterface()
}
}
Sample Project
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