On a desktop computer by far the most common "dApp browser" is MetaMask, which is merely a Chrome/Firefox extension. The mechanism is simply "a web browser" that gives the web page the ability (via some injected JavaScript object) to "request an Ethereum transaction be executed" (which costs money to do, and might even simply be the transfer of money). If it were possible to make browser extensions for MobileSafari people likely wouldn't bother making entire replacement browsers, as the experience is categorically worse.

Alternative browsers--built using Apple's browser--exist on the App Store; the issue here is that users are paying for something via a mechanism that isn't in-app purchases: Apple wants all payments in the world to flow through them, and so the idea of a decentralized payment future is incompatible with the App Store.

Wouldn't they remove regular Bitcoin and ethereum wallets too if they were trying to control payment flows

They did for quite a while. It was only relatively recently that Tim Cook reversed the policy and allowed crypto wallets to appear on iOS.

As far as I can tell, they model those apps like banking apps, or Venmo, or PayPal, which you will note are all also allowed. However, they model stuff you do with these dApp browsers as direct payments for a service. Apple has a rule in their App Store review guidelines that if you sell something, you must do it via in-app purchase.

Most dapps are more similar to investing like a tdameritrade, which is allowed in the app store. I guess that doesn't apply to all dapps though.

And yet you can purchase things in conventional e-commerce using a web browser on an iphone without Apple getting their cut.

How is this any different?

I am not defending Apple. I think Apple's behavior here should be illegal. I am merely stating what warped logic Apple seems to be locally applying here based on my understanding of the situation, from the perspective of their ludicrous, vague, and inconsistent policies.

E-commerce presumably falls under “physical goods” in Apple’s eyes, which is allowed.

Which seems rather arbitrary, it's not like you can't buy digital goods from Steam over the web.

This is yet another reason we must fight these proprietary app walled gardens. It's a clear regression from the open web.

For a while, you couldn't have Steam Link on iOS because it would be "bad" for Apple if you did buy a PC game through a live stream of your desktop.

https://9to5mac.com/2019/05/15/steam-link-ios-launch/

This is a fairly good explanation on stackexchange: https://ethereum.stackexchange.com/a/384

Excerpt (in the context of Ethereum, a smart contract platform):

> A DApp has its backend code running on a decentralized peer-to-peer network. Contrast this with an app where the backend code is running on centralized servers.

> A DApp can have frontend code and user interfaces written in any language (just like an app) that can make calls to its backend. Furthermore, its frontend can be hosted on decentralized storage such as Swarm or IPFS.

> If an app=frontend+server, since Ethereum contracts are code that runs on the global Ethereum decentralized peer-to-peer network, then: DApp = frontend + contracts

How does the web3 or whatever js running in your web browser know what gateway to use to interface with the blockchain? What if that gateway goes down? How does it or any ETH or Bittorent node bootstrap in general?

The web3.js file doesn't pick your gateway. MetaMask uses a default gateway from Infura, but you can switch to another such as Cloudflare's gateway or a local node.

The web3 service host name is configurable by the user (with some defaults for batteries included user experience).

I made/am working on a DApp that does some stuff involving ANSI art as tokens with some additional properties that have rules that get enforced by the smart contract, which is essentially the back end. While the site sort of functions without being connected to the blockchain (there's a crappy database backed backend too), there is an entirely different set of data that's stored there that is not entirely in my control - only so much as the smart contract/backend coding permits once deployed to the Blockchain Virtual Machine.

Instead of talking to an API connected to a database, it's connected to an ABI talking to the blockchain. Someone could directly interface with that, or use my client, or build their own etc, it's open on the blockchain. Read operations are free unless specified, write operations generally have an implicit cost of the smart contracts currency at least with what I've used, which was Ethereum.

What is a "DApp?"

Decentralized App

You can create front facing software that only interfaces with blockchain(s). To create a wallet you create a pub + private key pair. You can then sign tx's with that. A DApp can enable transfer of assets between addresses, calling smart contract functions in deployed smart contracts, and the frontend keeps you updated on the tx statuses. Essentially they are created for privacy and security reasons, and to execute scripting code from a mobile app, which is stored at a deployed smart contract address. I'm not sure what Apple's motivation is here, compliance or legal issues would probably be their biggest complaint? Or is this their attempt to squash an app store within their App Store?

I believe Apple forbids running third-party code it hasn’t approved, with some exceptions for educational apps.

> I believe Apple forbids running third-party code it hasn’t approved, with some exceptions for educational apps.

Exceptions list:

1) Content served over HTTP(S) such as JavaScript.

2) WeChat.

3) ...

WeChat/LINE/AliChat etc all do their apps with JS in a webview, which apple explicitly allows.

Which is probably why Firefox Mobile on iOS can't have extensions, which is a shame.

I see, it's like when developers build automatic deployment into their apps to avoid app review.

Yeah but these apps are just html and JavaScript which is normally allowed.

Yeah Apple explicitly states that in their guidelines. Why would they ban it?

dApp is kind of a flexible word, but the typical unifying feature is that the user has custody of a private key they use for signing transactions on a distributed ledger.

Most dApps (at least the ones you access through a dApp browser) have UIs built using regular web technology, and served over http.

As for why Google/Apple are doing this, I can only imagine that it threatens their walled garden by giving web users more access to payments that they'd rather monetize.