OC中指针的改变和要点
直接看例子！！！

////  main.m//  PointerPointer////  Created by Rayln Guan on 8/30/13.//  Copyright (c) 2013 Rayln Guan. All rights reserved.//#import <Foundation/Foundation.h>void test1(NSString *str){    str = @"567";}void test2(NSString **str){    *str = @"678";}int main(int argc, const char * argv[]){    @autoreleasepool {        NSString *str = @"12345";        test1(str);        NSLog(@"str:%@", str); //打印出12345                test2(&str);        NSLog(@"&str:%@", str); //打印出678            }    return 0;}