NSString *str = @"Sample String";

@class Point, Rectangle;

NSString* nsStr = @"hi I'm NSString";
const char* strTmp = [nsStr UTF8String];

char szText[] = "hi...";
NSString* nsStr = [NSString stringWithUTF8String: szText];

NSData *recieveData = . . . ;
NSString *strData = [[NSString alloc]initWithData:recieveData encoding:NSUTF8StringEncoding];
NSLog(@"data:%@", strData);

if (!obj) { ... }