var data=Data()
var array=[UInt8]()
var str=""

//Data[UInt8]
data.append(10)
array=[UInt8](data)
print(array)//[10]

//[UInt8]转Data
array=[1,2,3,4,5]
data=Data(array)
print(data.count)//5

//Data转String
data.removeAll()
data.append(contentsOf:[0x31,0x32,0x33])
str=String(data:data,encoding:.utf8)!
print(str)

//String转Data
str="world"
data=str.data(using: .utf8)!
print(data.count)//5

//String转[UInt8]
str="hello"
array=[UInt8](str.utf8)
print(array)//[104, 101, 108, 108, 111]

//[UInt8]转String
array=[0x39,0x39,0x39]
str=String(bytes:array,encoding: .utf8)!
print(str)//999