I would like to produce a GRanges from a XStringViews object. However I am getting an error:

library(BSgenome.Hsapiens.UCSC.hg19)
hg19=BSgenome.Hsapiens.UCSC.hg19

tata <- DNAString("TATAAA")

ma <- matchPattern(tata,hg19$chr22)

gma <- as(ma, "GRanges")
Error in as(ma, "GRanges") : 
  no method or default for coercing “XStringViews” to “GRanges”

Some idea how to successfully make a conversion between this two classes?

What is your expected result? There is not enough information to construct a GRanges from an XStringViews. Note that any Views is composed of a subject and a set of ranges, and those ranges can be extracted via ranges().  So if you wanted a GRanges with those ranges on chr22, do: GRanges("chr22", ranges(ma)).

But perhaps you want to do this over the whole genome, in which case this is a lot easier:

gma <- vmatchPattern(tata, hg19)