No "SWISH", so how do I pay for things in Sweden?

In Sweden, like most European countries, you can use your credit card for contactless pay, or pay and sign a paper slip like you f=do at home.

You can also add your credit card to your Apple or Google wallet and pay contactless by phone.

I'm honestly not sure what "Swish" is, but the few Swedes I know just use a credit card or their local debit card.

There certainly are places that simply no longer take cash, Sweden as a whole is pretty close to being cashless.

I assume that I can use my debit card and my credit card

Yes I think that's the only way to go, I had the same problem as a short-term resident of Sweden, we are not allowed a personal number so I could not get a bank account/swish account. Cash is basically non-existent in most transactions.

Most store and restaurant payments are made with card (or a phone connected to a card). Swish is popular for transaction between people, for example for splitting a bill, at the flea market or for a "craigslist type" of transaction. Also when buying from non-businesses like buying fika from a sports club. Very small businesses like a less touristy Christmas market vendor usually accept two out of card, Swish and cash and the market visitors bring two of the same so there is always a match.

Swish is a payment app. But I'm not sure about the statement that most Swedes use Swish to pay at stores and restaurant. My feeling is that most payments at stores and restaurants are done by card (Visa or Mastercard). Even if Swish is gaining ground. Especially at markets where small vendors usually find Swish easier and cheaper to handle compared to cards. But cash is also used.

In 2022 I saw a "Swish or cash only" sign at a food stand in Helsingborg, but that was the only time I encountered that. I didn't shop at flea markets or farmer's markets, however.

Credit/debit cards work fine (tap to pay will be helpful, especially for public transport) and will not be a problem to use in normal stores/restaurants/hotels/etc. After all, most places want to be able to serve tourists. Swish is more or less equivalent to Venmo in the US, but directly connected to your bank account. People use it to send small amounts to each other as well as make purchases. The only places I have seen that you could say might "prefer" Swish are food trucks and other small independent individual vendors (like the guy selling flowers at a local market, to name one example), I assume because they want to avoid credit card fees. Haven't used cash in Sweden for years and can't use Swish, but never had any problem. Unless you plan on patronizing a lot of these kind of small vendors, I don't think you will need to worry about it either.