tagSession (Standard NFC Tag Session)

The tagSession module provides common APIs for establishing connections and transferring data.

NOTE

The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import tag from '@ohos.nfc.tag';

tagSession

Provides common APIs for establishing connections and transferring data. tagSession is the base class of all NFC tag technologies.

A child class instance is required to access the following interfaces. You can use getXXX() to obtain a child class instance.

The specific API varies with the NFC tag technology in use. For details, see NFC Tags.

tagSession.getTagInfo

getTagInfo(): tag.TagInfo

Obtains the tagInfo object provided by the NFC service when the tag is dispatched.

NOTE This API is supported since API version 7 and deprecated since API version 9. You are advised to use tag.getTagInfo.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Return value

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

let tagInfo = tag.getIsoDep(tagInfo).getTagInfo(); 
console.log("tag tagInfo: " + tagInfo);

tagSession.connectTag

connectTag(): boolean;

Connects to this tag. Call this API to set up a connection before reading data from or writing data to a tag.

NOTE This API is supported since API version 7 and deprecated since API version 9. You are advised to use tagSession.connect.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Return value

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

let connectStatus = tag.getIsoDep(tagInfo).connectTag(); 
console.log("connectStatus: " + connectStatus);

tagSession.connect⁹⁺

connect(): void;

Connects to this tag. Call this API to set up a connection before reading data from or writing data to a tag.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Error codes

For details about the error codes, see NFC Error Codes.

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

try {
    tag.getIsoDep(tagInfo).connect(); 
    console.log("tag connect success");
} catch (busiError) {
    console.log("tag connect busiError: " + busiError);
}

tagSession.reset()

reset(): void

Resets the connection to this tag.

NOTE This API is supported since API version 7 and deprecated since API version 9. You are advised to use tagSession.resetConnection.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

tag.getIsoDep(tagInfo).reset(); 

tagSession.resetConnection()⁹⁺

resetConnection(): void

Resets the connection to this tag.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Error codes

For details about the error codes, see NFC Error Codes.

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

try {
    tag.getIsoDep(tagInfo).resetConnection(); 
    console.log("tag resetConnection success");
} catch (busiError) {
    console.log("tag resetConnection busiError: " + busiError);
}

tagSession.isTagConnected

isTagConnected(): boolean

Checks whether the tag is connected.

NOTE This API is supported since API version 7 and deprecated since API version 9. You are advised to use tagSession.isConnected.

System capability: SystemCapability.Communication.NFC.Tag

Return value

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

let isTagConnected = tag.getIsoDep(tagInfo).isTagConnected(); 
console.log("isTagConnected: " + isTagConnected);

tagSession.isConnected⁹⁺

isConnected(): boolean

Checks whether the tag is connected.

System capability: SystemCapability.Communication.NFC.Tag

Return value

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

try {
    var isConnected = tag.getIsoDep(tagInfo).isConnected(); 
    console.log("tag isConnected = " + isConnected);
} catch (busiError) {
    console.log("tag isConnected busiError: " + busiError);
}

tagSession.getMaxSendLength

getMaxSendLength(): number

Obtains the maximum length of the data that can be sent to this tag.

NOTE This API is supported since API version 7 and deprecated since API version 9. You are advised to use tagSession.getMaxTransmitSize.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Return value

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

let maxSendLen = tag.getIsoDep(tagInfo).getMaxSendLength(); 
console.log("tag maxSendLen: " + maxSendLen);

tagSession.getMaxTransmitSize⁹⁺

getMaxTransmitSize(): number

Obtains the maximum length of the data that can be sent to this tag.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Return value

Error codes

For details about the error codes, see NFC Error Codes.

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

try {
    var maxTransmitSize = tag.getIsoDep(tagInfo).getMaxTransmitSize(); 
    console.log("tag maxTransmitSize = " + maxTransmitSize);
} catch (busiError) {
    console.log("tag getMaxTransmitSize busiError: " + busiError);
}

tagSession.getSendDataTimeout

getSendDataTimeout(): number

Obtains the timeout period for sending data to this tag, in milliseconds.

NOTE This API is supported since API version 7 and deprecated since API version 9. You are advised to use tagSession.getTimeout.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Return value

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

let sendDataTimeout = tag.getIsoDep(tagInfo).getSendDataTimeout(); 
console.log("tag sendDataTimeout: " + sendDataTimeout);

tagSession.getTimeout⁹⁺

getTimeout(): number

Obtains the timeout period for sending data to this tag, in milliseconds.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Return value

Error codes

For details about the error codes, see NFC Error Codes.

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

try {
    var timeout = tag.getIsoDep(tagInfo).getTimeout(); 
    console.log("tag timeout = " + timeout);
} catch (busiError) {
    console.log("tag getTimeout busiError: " + busiError);
}

tagSession.setSendDataTimeout

setSendDataTimeout(timeout: number): boolean

Sets the timeout period for sending data to this tag, in milliseconds.

NOTE This API is supported since API version 7 and deprecated since API version 9. You are advised to use tagSession.setTimeout.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Parameters

Return value

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

let timeoutMs = 700;  // Change it as required.
let setStatus = tag.getIsoDep(tagInfo).setSendDataTimeout(timeoutMs); 
console.log("tag setSendDataTimeout setStatus: " + setStatus);

tagSession.setTimeout⁹⁺

setTimeout(timeout: number): void

Sets the timeout period for sending data to this tag, in milliseconds.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Parameters

Error codes

For details about the error codes, see NFC Error Codes.

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

let timeoutMs = 700;  // Change it as required.
try {
    tag.getIsoDep(tagInfo).setTimeout(timeoutMs); 
    console.log("tag setTimeout success");
} catch (busiError) {
    console.log("tag setTimeout busiError: " + busiError);
}

tagSession.sendData

sendData(data: number[]): Promise<number[]>

Sends data to this tag. This API uses a promise to return the result.

NOTE This API is supported since API version 7 and deprecated since API version 9. You are advised to use tagSession.transmit.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Parameters

Return value

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

// Connect to the tag if it is not connected.
if (!tag.getIsoDep(tagInfo).isTagConnected()) {
    if (!tag.getIsoDep(tagInfo).connectTag()) {
        console.log("tagSession connectTag failed.");
        return;
    }
}

let cmdData = [0x01, 0x02, 0x03, 0x04]; // Change it as required.
tag.getIsoDep(tagInfo).sendData(cmdData).then((response) => {
    console.log("tagSession sendData Promise response: " + response);
}).catch((err)=> {
    console.log("tagSession sendData Promise err: " + err);
});

tagSession.sendData

sendData(data: number[], callback: AsyncCallback<number[]>): void

Sends data to this tag. This API uses an asynchronous callback to return the result.

NOTE This parameter is supported since API version 7 and discarded since API version 9. You are advised to use tagSession.transmit.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Parameters

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

// Connect to the tag if it is not connected.
if (!tag.getIsoDep(tagInfo).isTagConnected()) {
    if (!tag.getIsoDep(tagInfo).connectTag()) {
        console.log("tagSession connectTag failed.");
        return;
    }
}

let cmdData = [0x01, 0x02, 0x03, 0x04]; // Change it as required.
tag.getIsoDep(tagInfo).sendData(cmdData, (err, response)=> {
    if (err) {
        console.log("tagSession sendData AsyncCallback err: " + err);
    } else {
        console.log("tagSession sendData AsyncCallback response: " + response);
    }
});

tagSession.transmit⁹⁺

transmit(data: number[]): Promise<number[]>

Transmits data to this tag. This API uses a promise to return the result.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Parameters

Return value

Error codes

For details about the error codes, see NFC Error Codes.

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

// Connect to the tag if it is not connected.
try {
    if (!tag.getIsoDep(tagInfo).isConnected()) {
        tag.getIsoDep(tagInfo).connect();
    }
} catch (busiError) {
    console.log("tag connect busiError: " + busiError);
    return;
}

let cmdData = [0x01, 0x02, 0x03, 0x04]; // Change it as required.
try {
    tag.getIsoDep(tagInfo).transmit(cmdData).then((response) => {
        console.log("tagSession transmit Promise response: " + response);
    }).catch((err)=> {
        console.log("tagSession transmit Promise err: " + err);
    });
} catch (busiError) {
    console.log("tag transmit busiError: " + busiError);
    return;
}

tagSession.transmit⁹⁺

transmit(data: number[], callback: AsyncCallback<number[]>): void

Transmits data to this tag. This API uses an asynchronous callback to return the result.

Required permissions: ohos.permission.NFC_TAG

System capability: SystemCapability.Communication.NFC.Tag

Parameters

Error codes

For details about the error codes, see NFC Error Codes.

Example

import tag from '@ohos.nfc.tag';

// tagInfo is an object provided by the NFC service when a tag is dispatched.
// getXXX can be getIsoDep, getNdef, getMifareClassic, or any other getter for NFC tags.

// Connect to the tag if it is not connected.
try {
    if (!tag.getIsoDep(tagInfo).isConnected()) {
        tag.getIsoDep(tagInfo).connect();
    }
} catch (busiError) {
    console.log("tag connect busiError: " + busiError);
    return;
}

let cmdData = [0x01, 0x02, 0x03, 0x04]; // Change it as required.
try {
    tag.getIsoDep(tagInfo).transmit(cmdData, (err, response)=> {
        if (err) {
            console.log("tagSession transmit AsyncCallback err: " + err);
        } else {
            console.log("tagSession transmit AsyncCallback response: " + response);
        }
    });
} catch (busiError) {
    console.log("tag transmit busiError: " + busiError);
    return;
}