If you have a job in New Zealand, it should be relatively simple to obtain Permanent Residence through the Skilled Migrant Category, however, if you fall short of points at the Expression of Interest stage, then you should be able to apply for a Work to Residency visa which is valid for 2 years and gives you valuable additional points if you apply for permanent residency at the end of the 2 year period.
If you already have a job offer, the same rules as those shown on the link ‘You are looking for a job’; you will still need to meet all the entry requirements stipulated, however, by already having a job offer, you will be able to apply for your visa in advance of coming to New Zealand.