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NFC Forum devices support two modes of communications. The first mode, peer-to-peer communications, is used to communicate between two NFC Forum devices. The second mode, master/slave communications, is used to communicate between an NFC Forum device and an NFC Forum Tag or Contactless Card. The
targetDetected() signal is emitted when a target device enters communications range. Communications can be initiated from the slot connected to this signal.
NFC Forum devices generally operate as the master in master/slave communications. Some devices are also capable of operating as the slave, so called Card Emulation mode. In this mode the local NFC device emulates a NFC Forum Tag or Contactless Card.
Applications can connect to the
targetLost() signals to get notified when an NFC Forum Tag enters or leaves proximity. Before these signals are emitted target detection must be started with the
startTargetDetection() function. Target detection can be stopped with the
stopTargetDetection() function. When the target is no longer required the target should be deleted as other applications may be blocked from accessing the target.
Constructs a new near field manager with
This enum describes the different states a NFC adapter can have.
The nfc adapter is offline.
The nfc adapter is turning on.
The nfc adapter is online.
The nfc adapter is turning off.
This signal is emitted whenever the
state of the NFC adapter changed.
Currently, this signal is only emitted on Android.
- Return type:
true if the device has a NFC adapter and it is turned on; otherwise returns
- Return type:
true if the underlying device has a NFC adapter; otherwise returns
false. If an
accessMethod is given, the function returns
true only if the NFC adapter supports the given
message – str
Sets the message shown to the user by the system. If the target detection is running the
message will be updated immediately and can be used as a progress message. The last message set before a call to
startTargetDetection() without an error message is used as a success message. If the target detection is not running the
message will be used as the initial message when the next detection is started. By default no message is shown to the user.
Currently, this function only has an effect on iOS because a popup is shown by the system during the scan. On iOS, this
message is mapped to the alert message which is shown upon successful completion of the scan. Other platforms will ignore
- Return type:
Starts detecting targets and returns
true if target detection is successfully started; otherwise returns
false. Causes the
targetDetected() signal to be emitted when a target is within proximity. Only tags with the given
accessMethod will be delivered. Active detection continues until
stopTargetDetection() has been called.
To detect targets with a different
stopTargetDetection() must be called first.
On iOS it is impossible to start target detection for both NdefAccess and TagTypeSpecificAccess at the same time. So if AnyAccess is selected, NdefAccess will be used instead.
errorMessage – str
On iOS, detected targets become invalid after this call (e.g. an attempt to write or read NDEF messages will result in an error).
errorMessage is provided, this is a hint to the system that the goal, the application had, was not reached. The
errorMessage and a matching error icon are shown to the user. Calling this function with an empty
errorMessage, implies a successful operation end; otherwise an
errorMessage should be passed to this function.
errorMessage only has an effect on iOS because a popup is shown by the system during the scan where the
errorMessage is visible. Other platforms will ignore this parameter.
This signal is emitted whenever a target is detected. The
target parameter represents the detected target.
This signal will be emitted for all detected targets.
Do not delete
target from the slot connected to this signal, instead call
target is deleted before it moves out of proximity the
targetLost() signal will not be emitted.
This signal is emitted whenever the target detection is stopped.
Mostly this signal is emitted when
stopTargetDetection() has been called. Additionally the user is able to stop the detection on iOS within a popup shown by the system during the scan, which also leads to emitting this signal.
This signal is emitted whenever a target moves out of proximity. The
target parameter represents the lost target.
Do not delete
target from the slot connected to this signal, instead use