iOS Barometer SeaLevel Height
<p>Im Making an iOS App for Mountain Climbers to get the Height from <strong>SeaLevel</strong> , Currently Im stuck here. Im using iOS Barometer to get the details , but it only gives <strong>Pressure,Relative altitude and timestamp</strong> . is there a calculation to get the <strong>height from sea level</strong> ? 
I'm using following way to get the values. I'm using <strong>CMAltimeter</strong></p>

<pre><code>NSNumberFormatter *formatter = [[NSNumberFormatter alloc]init];
formatter.maximumFractionDigits = 2;
formatter.minimumIntegerDigits = 1;

NSNumber *timestamp = [NSNumber numberWithDouble:altitudeData.timestamp];
NSString *timeInterval = [NSString stringWithFormat:@"%@", [formatter stringFromNumber:timestamp]];
NSString *altitude = [NSString stringWithFormat:@"%@", [formatter stringFromNumber:altitudeData.relativeAltitude]];
NSString *pressure = [NSString stringWithFormat:@"%@", [formatter stringFromNumber:altitudeData.pressure]];

self.label1.text = [NSString stringWithFormat:@"Time Interval: \n%@", timeInterval];
self.label2.text = [NSString stringWithFormat:@"Relative Altitude: \n%@", altitude];
self.label3.text = [NSString stringWithFormat:@"Air Pressure: \n%@", pressure];
</code></pre>