I can get the value of Wifi RSSI. but don't know how to convert it into level of Wifi strength as we can see in the menubar in Mac OSX (If I receive a strong Wifi, the wifi status will be bold black on all 4 lines of wifi icon).
Is there any methods or library that I can use to do this? Thx in advance.
I don't think you'll find anything in the API to do this.
I think you might have to Use Science™ and do a manual check, literally walking away from your WiFi access point with laptop in hand, noting down the RSSI values at which the WiFi signal indicator icon changes. Do this a few times and you'll likely find a correlation. I can't imagine it would take more than ten or fifteen minutes to get a good range of sample values.
It's probably worth trying it with more than one type of Mac, if possible.
There is no public API for this. You'll have to figure it out yourself. You might be able to use something simple like (RSSI+100)/8 and then clamp the result between 0 and 4 bars. Also, you'll want to use a rolling average over a few seconds to keep the bars from jumping around if the signal ends up at a boundary case or jumps around. PS: AFAIK, Apple uses a more complex algorithm which takes Transmit Rate into consideration.
