Objective C " * " syntax and usage - ios

Question

I am re-writing the particle filter library of iOS in Swift from Objective C which is available on Bitbucket and I have a question regarding a syntax of Objective C which I cannot understand.
The code goes as follows:
- (void)setRssi:(NSInteger)rssi {
_rssi = rssi;
// Ignore zeros in average, StdDev -- we clear the value before setting it to
// prevent old values from hanging around if there's no reading
if (rssi == 0) {
self.meters = 0;
return;
}
self.meters = [self metersFromRssi:rssi];
NSInteger* pidx = self.rssiBuffer;
*(pidx+self.bufferIndex++) = rssi;
if (self.bufferIndex >= RSSIBUFFERSIZE) {
self.bufferIndex %= RSSIBUFFERSIZE;
self.bufferFull = YES;
}
if (self.bufferFull) {
// Only calculate trailing mean and Std Dev when we have enough data
double accumulator = 0;
for (NSInteger i = 0; i < RSSIBUFFERSIZE; i++) {
accumulator += *(pidx+i);
}
self.meanRssi = accumulator / RSSIBUFFERSIZE;
self.meanMeters = [self metersFromRssi:self.meanRssi];
accumulator = 0;
for (NSInteger i = 0; i < RSSIBUFFERSIZE; i++) {
NSInteger difference = *(pidx+i) - self.meanRssi;
accumulator += difference*difference;
}
self.stdDeviationRssi = sqrt( accumulator / RSSIBUFFERSIZE);
self.meanMetersVariance = ABS(
[self metersFromRssi:self.meanRssi]
- [self metersFromRssi:self.meanRssi+self.stdDeviationRssi]
);
}
}
The class continues with more code and functions which are not important and what I do not understand are these two lines
NSInteger* pidx = self.rssiBuffer;
*(pidx+self.bufferIndex++) = rssi;
Variable pidx is initialized to the size of a buffer which was previously defined and then in the next line the size of that buffer and buffer plus one is equal to the RSSI variable which is passed as a parameter in the function.
I assume that * has something to do with reference but I just can't figure out the purpose of this line. Variable pidx is used only in this function for calculating trailing mean and standard deviation.

Answer 1

Let explain those code:
NSInteger* pidx = self.rssiBuffer; means that you are getting pointer of the first value of the buffer.
*(pidx+self.bufferIndex++) = rssi; means that you are setting the value of the buffer at index 0+self.bufferIndex to rssiand then increase bufferIndex by 1. Thanks to #Jakub Vano point it out.
In C++, it will look like that
int self.rssiBuffer[1000]; // I assume we have buffer like that
self.rssiBuffer[self.bufferIndex++] = rssi