[英]UnsafePointer in Swift 3
I know this question was asked several times but I really don't understand it.我知道这个问题被问了好几次,但我真的不明白。
I want to extract a value from a bluetooth device (miband).我想从蓝牙设备(miband)中提取一个值。 In swift 2 it worked like this:在 swift 2 中它是这样工作的:
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
if characteristic.uuid.uuidString == "FF06" {
let value = UnsafePointer<Int>(characteristic.value!.bytes).memory
print("Steps: \(value)")
}
}
But in swift 3 it throws an error:但是在 swift 3 中它会抛出一个错误:
Cannot invoke initializer for type 'UnsafePointer<Int>' with an argument list of type '(UnsafeRawPointer)'
And I have no idea how to migrate that to swift 3.而且我不知道如何将其迁移到 swift 3。
You can use withUnsafeBytes
with pointee
:您可以使用withUnsafeBytes
与pointee
:
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
if characteristic.uuid.uuidString == "FF06" {
let value = characteristic.value!.withUnsafeBytes { (pointer: UnsafePointer<Int>) -> Int in
return pointer.pointee
}
print("Steps: \(value)")
}
}
If the UnsafePointer
was pointing to an array of Pointee
, then you could use the subscript operator, eg pointer[0]
, pointer[1]
, etc., rather than pointer.pointee
.如果UnsafePointer
指着的数组Pointee
,则可以使用下标操作符,例如pointer[0]
pointer[1]
等等,而不是pointer.pointee
。
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