NSString,NSData,char的转换
1. NSString转化NSData

NSData* aData = [@"a nsstring" dataUsingEncoding: NSUTF8StringEncoding];

2.NSData转化NSString

NSString* aString = [[NSString alloc] initWithData:aData encoding:NSUTF8StringEncoding];

3.NSString转化char

char cstr[10];cstr =[aString UTF8String];

4.NSData转化char

char* cstr=[aData bytes];

5.char转化NSString

- (id)initWithUTF8String:(const char *)bytesNSString *bString = [[NSString alloc] initWithUTF8String:cstr];

6.char转化NSData

NSData *data = [NSData dataWithBytes:cstr length:strlen(cstr)];