Measuring cellular signal strength

Solution 1:

Get signalStreght IOS9:

UIApplication *app = [UIApplication sharedApplication];  
NSArray *subviews = [[[app valueForKey:@"statusBar"]     valueForKey:@"foregroundView"] subviews];  
NSString *dataNetworkItemView = nil;  
     for (id subview in subviews) {  
   if([subview isKindOfClass:[NSClassFromString(@"UIStatusBarSignalStrengthItemView") class]])  
   {  
        dataNetworkItemView = subview;  
        break;  
    }  
 }  
int signalStrength = [[dataNetworkItemView valueForKey:@"signalStrengthRaw"] intValue];  
NSLog(@"signal %d", signalStrength);

Solution 2:

It is not very hard.

1. Link CoreTelephony.framework in your Xcode project
2. Add the following lines where you need it

Code:

int CTGetSignalStrength(); // private method (not in the header) of Core Telephony

- (void)aScanMethod
{
    NSLog(@"%d", CTGetSignalStrength()); // or do what you want
}

And you are done.

Update May 2016

Apple removed this opportunity.

Solution 3:

I briefly looked at the VAFieldTest project located at Github.

There seems to be getSignalStrength() and register_notification() functions in Classes/VAFieldTestViewController.m that might be interesting to you as they call into CoreTelephony.framework.

I am pretty confident that some of the used calls are undocumented in the CoreTelephony framework documentation from Apple and therefore private - any app in the AppStore must have slipped passed inspection.

Solution 4:

To get signal streght in iOS 9 or above in Swift 3, without using the private API from CoreTelephony - CTGetSignalStrength(). Just scouring the statusBar view.

func getSignalStrength() -> Int {

    let application = UIApplication.shared
    let statusBarView = application.value(forKey: "statusBar") as! UIView
    let foregroundView = statusBarView.value(forKey: "foregroundView") as! UIView
    let foregroundViewSubviews = foregroundView.subviews

    var dataNetworkItemView:UIView!

    for subview in foregroundViewSubviews {
        if subview.isKind(of: NSClassFromString("UIStatusBarSignalStrengthItemView")!) {
            dataNetworkItemView = subview
            break
        } else {
            return 0 //NO SERVICE
        }
    }

    return dataNetworkItemView.value(forKey: "signalStrengthBars") as! Int

}

Attention: If the status bar is hidden, the key "statusBar" will return nil.