import FungibleToken from 0xa0225e7000ac82a9 import FlowToken from 0x4445e7ad11568276 import MetadataViews from 0xb6763b4399a888c8 import ViewResolver from 0xb6763b4399a888c8 import NonFungibleToken from 0xb6763b4399a888c8 import ScopedFTProviders from 0x715c57f7a59bc39b import EVM from 0xb6763b4399a888c8 import FlowEVMBridgeUtils from 0x715c57f7a59bc39b import FlowEVMBridge from 0x715c57f7a59bc39b import FlowEVMBridgeConfig from 0x715c57f7a59bc39b /// This transaction bridges an NFT from EVM to Cadence assuming it has already been onboarded to the FlowEVMBridge /// NOTE: The ERC721 must have first been onboarded to the bridge. This can be checked via the method /// FlowEVMBridge.evmAddressRequiresOnboarding(address: self.evmContractAddress) /// /// @param nftContractAddress: The Flow account address hosting the NFT-defining Cadence contract /// @param nftContractName: The name of the NFT-defining Cadence contract /// @param id: The ERC721 id of the NFT to bridge to Cadence from EVM /// transaction(nftContractAddress: Address, nftContractName: String, ids: [UInt256]) { let nftType: Type let collection: &{NonFungibleToken.Collection} let scopedProvider: @ScopedFTProviders.ScopedFTProvider let coa: auth(EVM.Bridge) &EVM.CadenceOwnedAccount prepare(signer: auth(BorrowValue, CopyValue, IssueStorageCapabilityController, PublishCapability, SaveValue, UnpublishCapability) &Account) { /* --- Reference the signer's CadenceOwnedAccount --- */ // // Borrow a reference to the signer's COA self.coa = signer.storage.borrow(from: /storage/evm) ?? panic("Could not borrow COA from provided gateway address") // Get the ERC721 contract address for the given NFT type self.nftType = FlowEVMBridgeUtils.buildCompositeType( address: nftContractAddress, contractName: nftContractName, resourceName: "NFT" ) ?? panic("Could not construct NFT type") /* --- Reference the signer's NFT Collection --- */ // // Borrow a reference to the NFT collection, configuring if necessary let viewResolver = getAccount(nftContractAddress).contracts.borrow<&{ViewResolver}>(name: nftContractName) ?? panic("Could not borrow ViewResolver from NFT contract") let collectionData = viewResolver.resolveContractView( resourceType: self.nftType, viewType: Type() ) as! MetadataViews.NFTCollectionData? ?? panic("Could not resolve NFTCollectionData view") if signer.storage.borrow<&{NonFungibleToken.Collection}>(from: collectionData.storagePath) == nil { signer.storage.save(<-collectionData.createEmptyCollection(), to: collectionData.storagePath) signer.capabilities.unpublish(collectionData.publicPath) let collectionCap = signer.capabilities.storage.issue<&{NonFungibleToken.Collection}>(collectionData.storagePath) signer.capabilities.publish(collectionCap, at: collectionData.publicPath) } self.collection = signer.storage.borrow<&{NonFungibleToken.Collection}>(from: collectionData.storagePath) ?? panic("Could not borrow collection from storage path") /* --- Configure a ScopedFTProvider --- */ // // Calculate the bridge fee - bridging from EVM consumes no storage, so flat fee let approxFee = FlowEVMBridgeUtils.calculateBridgeFee(bytes: 0) * UFix64(ids.length) // Issue and store bridge-dedicated Provider Capability in storage if necessary if signer.storage.type(at: FlowEVMBridgeConfig.providerCapabilityStoragePath) == nil { let providerCap = signer.capabilities.storage.issue( /storage/flowTokenVault ) signer.storage.save(providerCap, to: FlowEVMBridgeConfig.providerCapabilityStoragePath) } // Copy the stored Provider capability and create a ScopedFTProvider let providerCapCopy = signer.storage.copy>( from: FlowEVMBridgeConfig.providerCapabilityStoragePath ) ?? panic("Invalid Provider Capability found in storage.") let providerFilter = ScopedFTProviders.AllowanceFilter(approxFee) self.scopedProvider <- ScopedFTProviders.createScopedFTProvider( provider: providerCapCopy, filters: [ providerFilter ], expiration: getCurrentBlock().timestamp + 1.0 ) } execute { // Execute the bridge for id in ids { let nft: @{NonFungibleToken.NFT} <- self.coa.withdrawNFT( type: self.nftType, id: id, feeProvider: &self.scopedProvider as auth(FungibleToken.Withdraw) &{FungibleToken.Provider} ) self.collection.deposit(token: <-nft) } // Deposit the bridged NFT into the signer's collection // Destroy the ScopedFTProvider destroy self.scopedProvider } }

🎶Happy diving into the flow

Transaction

🎶Happy diving into the flow