objective c 不同数据类型转换

NSString 转 byte字节
NSData *strDataBytes = [@"$$" dataUsingEncoding:NSUTF8StringEncoding];

转换结果为｛0x24, 0x24};

int 转 byte
NSMutableData *myData = [[NSMutableData alloc] init];

int num = 1024;
[myData appendBytes:&num length:sizeof(num)];

Byte数组 转 NSData
Byte *bytes = {***};

NSData *strData = [NSData dataWithBytes:bytes length:strlen];

NSData 转 NSString
NSData *strData = ***;

NSString* string = [[NSString alloc] initWithData:strData encoding:NSUTF8StringEncoding];