How to test EDGE or GPRS or any other slow/bad network

Question

In my iOS app, I support to work online as well as offline. For this I have used Apple's Reachability code. Now I want to show user is offline if the cellular mobile network is EDGE or GPRS or bad/slow network. I have used the below code( Found solution ).

Code:

CTTelephonyNetworkInfo *telephonyInfo = [CTTelephonyNetworkInfo new];
NSLog(@"Current Radio Access Technology: %@", telephonyInfo.currentRadioAccessTechnology);
[NSNotificationCenter.defaultCenter addObserverForName:CTRadioAccessTechnologyDidChangeNotification 
                                                object:nil 
                                                 queue:nil 
                                            usingBlock:^(NSNotification *note) 
{
    NSLog(@"New Radio Access Technology: %@", telephonyInfo.currentRadioAccessTechnology);
}];

I did testing on device with 3G cellular mobile network and got CTRadioAccessTechnologyWCDMA successful. To test EDGE or GPRS or any other slow/bad network I used Network Link Conditioner from device's developer settings but still getting CTRadioAccessTechnologyWCDMA value.

EDIT:

After doing so many researches, I have found another solution which measures signal strength. I have tested this on iOS7 device it works but not in iOS8.4 device. Also I think this is private API so may apple will reject this.

Here is my code:

#import <CoreTelephony/CTTelephonyNetworkInfo.h>
#import <dlfcn.h>

int CTGetSignalStrength();

@implementation ViewController
-(int) getSignalStrength
{
    void *libHandle = dlopen("/System/Library/Frameworks/CoreTelephony.framework/CoreTelephony", RTLD_LAZY);
    int (*CTGetSignalStrength)();
    CTGetSignalStrength = dlsym(libHandle, "CTGetSignalStrength");
    if( CTGetSignalStrength == NULL) NSLog(@"Could not find CTGetSignalStrength");
    int result = CTGetSignalStrength();
    dlclose(libHandle);
    return result;
}

-(void)viewDidAppear:(BOOL)animated{
    [super viewDidAppear:animated];
    NSTimer* timer = [NSTimer timerWithTimeInterval:1.0f target:self selector:@selector(updateLabel) userInfo:nil repeats:YES];
    [[NSRunLoop mainRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
}
-(void)updateLabel{
    _lblSpeed.text = [NSString stringWithFormat:@"signal strength: %d\n", CTGetSignalStrength()];
    NSLog(@"signal strength: %d\n", CTGetSignalStrength());
}
@end

So any idea how we can test for EDGE or GPRS or any other slow/bad network? Is there any another solution/idea to proceed?