The injured party is indeed named Mustafa Jafari, and he has a number of convictions but only one is for a violent crime (assault).
He can not be said to be a "repeat offender of violent crimes" judging only from the published convictions, but he is a repeat offender, and has committed at least one assault before his incident with ASAP Rocky.
Identity of the injured party
A Swedish citizen can be uniquely identified by their personal identity number. This number contains the date of birth and will be printed on every official record where a person is identified.
The 541 page long police report (file number AM-92461-19, 2019-07-22, Warning: contains graphic content) from the ASAP Rocky incident lists a man named Jafari, Mustafa as the injured party on the first page. His personal identity number is listed in a few places in the same document.
I have collected a list of links to convictions against the same Mustafa Jafari that are currently doing the rounds on Swedish forums. I have verified the personal identity number in each and every verdict to make sure it is the same person.
They are written in Swedish, but I have tried to give a brief summary. There is an official Swedish-English law dictionary for Swedish legal terms which can be used in combination with google translate for the brave. It is for British English.
The documents, while being public records, are generally not freely available for download from an official source so someone has ordered the relevant documents and placed them online. The official case numbers are listed in case the files can no longer be accessed but according to the file hosting FAQ, they should be available as long as there is at least one download in a 5 year period.
As far as I know it is not possible to do a nationwide search for convictions but has to be done for each individual court. This means that the list may be incomplete.
List of convictions
The date is when the offense took place. Next the verdict and a short comment. Last is a link to the published conviction including the court name and file number.
- 2015-12-22 Guilty, aggravated assault, lowered to assault after appeal. Svea HR B 4587-16, Södertörns TR B 16838-15
- 2016-02-18 Guilty, shoplifting (one pair of jeans) Stockholms TR B 2805-16
- 2017-06-23 Guilty, minor drug offense (possession of Tramadol) Stockholms TR B 14680-17
- 2018-01-30 Guilty, minor drug offense (use of Heroin) Solna TR B 3666-18
Svea HR Svea Hovrätt Svea Court of Appeal
Södertörns TR Södertörns Tingsrätt Södertörn District Court
Stockholms TR Stockholms Tingsrätt Stockholm District Court
Solna TR Solna Tingsrätt Solna District Court