Objective C - 與Android互動時高低位轉換：

標籤：android   ios   c   

在與Android互動過程中，因為Android是從低位往高位讀，iOS是從高位往低位讀，所以互動資料需要進行轉換。

/* * convert big endian to little endian in C */uint16_t swap_uint16( uint16_t val );int16_t swap_int16( int16_t val );uint32_t swap_uint32( uint32_t val );int32_t swap_int32( int32_t val );int64_t swap_int64( int64_t val );uint64_t swap_uint64( uint64_t val );//////////////////////////////////////////////////////////////////////////////////////////////////////! Byte swap unsigned shortuint16_t swap_uint16( uint16_t val ){    return (val << 8) | (val >> 8 );}//! Byte swap shortint16_t swap_int16( int16_t val ){    return (val << 8) | ((val >> 8) & 0xFF);}//! Byte swap unsigned intuint32_t swap_uint32( uint32_t val ){    val = ((val << 8) & 0xFF00FF00 ) | ((val >> 8) & 0xFF00FF );    return (val << 16) | (val >> 16);}//! Byte swap intint32_t swap_int32( int32_t val ){    val = ((val << 8) & 0xFF00FF00) | ((val >> 8) & 0xFF00FF );    return (val << 16) | ((val >> 16) & 0xFFFF);}int64_t swap_int64( int64_t val ){    val = ((val << 8) & 0xFF00FF00FF00FF00ULL ) | ((val >> 8) & 0x00FF00FF00FF00FFULL );    val = ((val << 16) & 0xFFFF0000FFFF0000ULL ) | ((val >> 16) & 0x0000FFFF0000FFFFULL );    val = (val << 32) | ((val >> 32) & 0xFFFFFFFFULL);    return val;}uint64_t swap_uint64( uint64_t val ){    val = ((val << 8) & 0xFF00FF00FF00FF00ULL ) | ((val >> 8) & 0x00FF00FF00FF00FFULL );    val = ((val << 16) & 0xFFFF0000FFFF0000ULL ) | ((val >> 16) & 0x0000FFFF0000FFFFULL );    val = (val << 32) | (val >> 32);    return val;}

調用：

UInt64 recordTime = [[NSDate date] timeIntervalSince1970]*1000;UInt64 value = swap_uint64(recordTime);