I agree that uncontrolled immigration is not healthy but to blame it on that factor alone is taking the easy way out. If we are talking about Sverigedemokraterna here then it is important to note for example that the party got most votes in the elections last year in rural areas and least in the largest urban areas such as Stockholm and Göteborg (
Största städerna gillar inte SD | Nyheter | Aftonbladet ). Why is that Swedes out in the countryside who have little to no contact with immigrants on a daily basis are voting for this anti immigration party whereas Swedes in the urban areas who have regular contacts with immigrants (first and second) are not voting for an anti immigration party in the same numbers even though they are ones who are interacting with immigrants the most? The answer I believe comes down to "fear of the unknown". Immigrants are scary because we dont know anything about them, how do they think? What do they like? They are growing in numbers and we dont know anything about them, Panic!. Parties like Sverigedemokraterna play into this fear and do their best to instigate it further. However for Swedes living in urban areas they interact with immigrants on a regular basis and know that they are humans just like us. They become less and less "unknown" hence.
Another factor is the economy. Whenever the economy takes a hit right wing nationalism starts surging ahead. This isnt a Sweden or Europe only phenomenon but can be seen throughout the world. The idea that the "other" is taking our jobs is regularly used by xenophobic parties as part of their strategy to turn the native majority against the immigrant minority. The Nazis in Germany did exactly that with the Jews. So coming back to your response yes I agree that uncontrolled immigration is not healthy and Sweden along with other countries in the region should become more strict on this factor especially as far as learning the native language is concerned. However there are more factors at play here and xenophobic racists like Sverigedemokraterna will do their utmost to scare people into believing that immigrants are a threat to them and will unashamedly lie if this helps them in the process.