如何解决有没有办法让目标视图控制器在从 swift/Xcode 中的源视图控制器展开 segue 之后重新加载视图？
有没有办法让目标视图控制器在从 swift/Xcode 中的源视图控制器展开转场后重新加载视图？
即在目标视图控制器上运行 viewDidLoad()？或类似的东西？
解决方法
没有。在转场期间传回任何需要的信息是你的工作。视图控制器的工作是通过更新自己的界面来响应该信息。
假设我们正在使用 unwind segue 从 VC2 返回到 VC1。然后，您可以在 VC2 中实现 import struct
import bluetooth
# Advertising payloads are repeated packets of the following form:
# 1 byte data length (N + 1)
# 1 byte type (see constants below)
# N bytes type-specific data
_ADV_TYPE_FLAGS = const(0x01)
_ADV_TYPE_NAME = const(0x09)
_ADV_TYPE_UUID16_COMPLETE = const(0x3)
_ADV_TYPE_UUID32_COMPLETE = const(0x5)
_ADV_TYPE_UUID128_COMPLETE = const(0x7)
_ADV_TYPE_UUID16_MORE = const(0x2)
_ADV_TYPE_UUID32_MORE = const(0x4)
_ADV_TYPE_UUID128_MORE = const(0x6)
_ADV_TYPE_APPEARANCE = const(0x19)
_IRQ_CENTRAL_CONNECT = const(1 << 0)
_IRQ_CENTRAL_DISCONNECT = const(1 << 1)
_IRQ_GATTS_WRITE = const(1 << 2)
# org.bluetooth.characteristic.gap.appearance.xml
_ADV_APPEARANCE_GENERIC_COMPUTER = const(128)
# Generate a payload to be passed to gap_advertise(adv_data=...).
def advertising_payload(limited_disc=False,br_edr=False,name=None,services=None,appearance=0):
payload = bytearray()
def _append(adv_type,value):
nonlocal payload
payload += struct.pack('BB',len(value) + 1,adv_type) + value
_append(_ADV_TYPE_FLAGS,struct.pack('B',(0x01 if limited_disc else 0x02) + (0x00 if br_edr else 0x04)))
if name:
_append(_ADV_TYPE_NAME,name)
if services:
for uuid in services:
b = bytes(uuid)
if len(b) == 2:
_append(_ADV_TYPE_UUID16_COMPLETE,b)
elif len(b) == 4:
_append(_ADV_TYPE_UUID32_COMPLETE,b)
elif len(b) == 16:
_append(_ADV_TYPE_UUID128_COMPLETE,b)
# See org.bluetooth.characteristic.gap.appearance.xml
_append(_ADV_TYPE_APPEARANCE,struct.pack('<h',appearance))
return payload
def decode_field(payload,adv_type):
i = 0
result = []
while i + 1 < len(payload):
if payload[i + 1] == adv_type:
result.append(payload[i + 2:i + payload[i] + 1])
i += 1 + payload[i]
return result
def decode_name(payload):
n = decode_field(payload,_ADV_TYPE_NAME)
return str(n[0],'utf-8') if n else ''
def decode_services(payload):
services = []
for u in decode_field(payload,_ADV_TYPE_UUID16_COMPLETE):
services.append(bluetooth.UUID(struct.unpack('<h',u)[0]))
for u in decode_field(payload,_ADV_TYPE_UUID32_COMPLETE):
services.append(bluetooth.UUID(struct.unpack('<d',_ADV_TYPE_UUID128_COMPLETE):
services.append(bluetooth.UUID(u))
return services
class Bleuart:
def __init__(self,name,UUID_UART,UUID_TX,UUID_RX,rxbuf=100):
_UART_UUID = bluetooth.UUID(UUID_UART,)
_UART_TX = (bluetooth.UUID(UUID_TX),bluetooth.FLAG_NOTIFY,)
_UART_RX = (bluetooth.UUID(UUID_RX),bluetooth.FLAG_WRITE,)
_UART_SERVICE = (_UART_UUID,(_UART_TX,_UART_RX,),)
self._ble = bluetooth.BLE()
self._ble.active(True)
self._ble.irq(handler=self._irq)
((self._tx_handle,self._rx_handle,) = self._ble.gatts_register_services((_UART_SERVICE,))
# Increase the size of the rx buffer and enable append mode.
self._ble.gatts_set_buffer(self._rx_handle,rxbuf,True)
self._connections = set()
self._rx_buffer = bytearray()
self._handler = None
# Optionally add services=[_UART_UUID],but this is likely to make the payload too large.
self._payload = advertising_payload(name=name,appearance=_ADV_APPEARANCE_GENERIC_COMPUTER)
self._advertise()
def irq(self,handler):
self._handler = handler
def _irq(self,event,data):
# Track connections so we can send notifications.
if event == _IRQ_CENTRAL_CONNECT:
conn_handle,_,= data
self._connections.add(conn_handle)
elif event == _IRQ_CENTRAL_DISCONNECT:
conn_handle,= data
if conn_handle in self._connections:
self._connections.remove(conn_handle)
# Start advertising again to allow a new connection.
self._advertise()
elif event == _IRQ_GATTS_WRITE:
conn_handle,value_handle,= data
if conn_handle in self._connections and value_handle == self._rx_handle:
self._rx_buffer += self._ble.gatts_read(self._rx_handle)
if self._handler:
self._handler()
def any(self):
return len(self._rx_buffer)
def read(self,sz=None):
if not sz:
sz = len(self._rx_buffer)
result = self._rx_buffer[0:sz]
self._rx_buffer = self._rx_buffer[sz:]
return result
def write(self,data):
for conn_handle in self._connections:
self._ble.gatts_notify(conn_handle,self._tx_handle,data)
def close(self):
for conn_handle in self._connections:
self._ble.gap_disconnect(conn_handle)
self._connections.clear()
def _advertise(self,interval_us=500000):
self._ble.gap_advertise(interval_us,adv_data=self._payload)
if __name__ == '__main__':
import time
nom = 'esp32-uart-gcworks'
UUID_UART = '6E400001-B5A3-F393-E0A9-E50E24DCCA9E'
UUID_TX = '6E400003-B5A3-F393-E0A9-E50E24DCCA9E'
UUID_RX = '6E400002-B5A3-F393-E0A9-E50E24DCCA9E'
uart = Bleuart(nom,UUID_RX)
uart.close()
def on_rx():
print('rx: ',uart.read().decode().strip())
uart.irq(handler=on_rx)
nums = [4,8,15,16,23,42]
i = 0
try:
while True:
uart.write(str(nums[i]) + '\n')
i = (i + 1) % len(nums)
print(nums[i])
time.sleep_ms(1000)
except KeyboardInterrupt:
pass
，以某种为此目的而设计的方法将其所需的任何数据传递给 VC1。
或者当用户在 VC2 中时，使用标准的协议和委托模式将数据从 VC2 传送回 VC1。
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