//5的写法
/*
@autoreleasepool {
// insert code here...
NSLog(@"Hello, World!");
}
*/
//4的写法
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSLog(@"Hello, Wolrd");
[pool drain];
return 0;
需要设置Object-C Automatic Reference Counting值为No
