Convert speed: m/s to km/h - objective-c

Question

I am new to Objective-C and would like some help with converting MPS to KPH.
Below is my current string for speed. Can someone please point out what else is needed?
speed.text = newLocation.speed < 0 ? #"N/A": [NSString stringWithFormat:#"%d", (int)newLocation.speed];

Answer 1

m/s to km/h = (m/s) * (60*60)/1000
Or 1m/s = 3.6km/h
float speedInKilometersPerHour = newLocation.speed*3.6;
if (speedInKilometersPerHour!=0) {speed.text = [NSString stringWithFormat:#"%f", speedInKilometersPerHour];}
else speed.text = [NSString stringWithFormat:#"No Data Available"];

Answer 2

Assuming you mean Meters Per Second to Kilometers Per Hour, and you want us to modify your existing ternary, than this would do the job.
speed.text = (newLocation.speed < 0) ? (#"N/A") : ([NSString stringWithFormat:#"%d", (int)(newLocation.speed*3.6)]);
If the original speed in MPS was less than zero, than its not applicable, otherwise it converts it.
You should also probably round the result to the nearest integer, so that it's more accurate.
speed.text = (newLocation.speed < 0) ? (#"N/A") : ([NSString stringWithFormat:#"%d", (int)((newLocation.speed*3.6)+0.5)]);

Answer 3

Here is one way to do it (I've formatted it to be a little more readable):
if (newLocation.speed < 0)
speed.text = #"N/A";
else
speed.text = [NSString stringWithFormat:#"%d", (int)(newLocation.speed * 3.6)];
Note however, that you really should be using a number formatter to convert the number to a localized string before displaying it to the user so that it is formatted correctly in their own locale:
if (newLocation.speed < 0)
{
speed.text = #"N/A";
}
else
{
int speedKPH = (int)(newLocation.speed * 3.6);
NSNumber *number = [NSNumber numberWithInt:speedKPH];
NSNumberFormatter *formatter = [NSNumberFormatter new];
formatter.numberStyle = NSNumberFormatterDecimalStyle;
speed.text = [formatter stringFromNumber:number];
}