How to add point dynamicly

[kscorpio]

i test to add point

  ChartDataEntry * entry=[[ChartDataEntry alloc] initWithValue:index xIndex:index];
  index+=1;
   [self.scaleView.data addEntry:entry dataSetIndex:0];

1 where is the fault in the code
2 log out and in dataset the xIndex just can be an int type

[danielgindi]

Call notifyDataSetChanged. You might also want to "moveToX..."

[kscorpio]

    //! Y
       ChartDataSet * currentDataSet=self.scaleView.data.dataSets[0];
       NSInteger xIndex= currentDataSet.valueCount;
       ChartDataEntry * entry=[[ChartDataEntry alloc] initWithValue:yVal xIndex:xIndex];
       [currentDataSet addEntry:entry];
       //! X
       NSArray * xVal=_scaleView.data.xValsObjc;
       double lastX=[xVal.lastObject doubleValue];
       lastX +=0.1;
       [_scaleView.data addXValue:[NSString stringWithFormat:@"%f",lastX]];

       //!
       [self.scaleView notifyDataSetChanged];
       [self.scaleView moveViewToX:xIndex+1];

scene 1: before and zoom actions
when add new point to chart ,all the points are in the chart, the line does not move，
the x arix distance is become bigger

scene 2: after zoom in or zoom out
when add new point to chart ,the line can move.
it seems like a new pooint add from right ,and one or will disappear to left
but in fact the xarix is also become bigger？

,how to fix scene ? and the chart can perfor like an Oscilloscope， at the same time the number of point is constant value；