https://blog.youkuaiyun.com/PerfectW_1230zh-cnhttps://blog.youkuaiyun.com/https://blog.youkuaiyun.com/PerfectW_1230/article/details/41982173https://blog.youkuaiyun.com/PerfectW_1230/article/details/41982173PerfectW_1230Wed, 17 Dec 2014 15:19:07 +0800NSString是不可变字符串，字符串对象一旦创建出来，其内容不可以被改变。  2>创建字符串 //最简单的创建方式 NSString *s1 = @"jack"; NSStri]]>https://blog.youkuaiyun.com/PerfectW_1230/article/details/41981881https://blog.youkuaiyun.com/PerfectW_1230/article/details/41981881PerfectW_1230Wed, 17 Dec 2014 15:04:53 +0800set方法的作用: 用来设置对象的成员变量，可以在方法实现中过滤掉一些不合理的值，这样不论外界传什么样的垃圾值，都能保证内部的业务逻辑是对的。  2>g]]>https://blog.youkuaiyun.com/PerfectW_1230/article/details/41978635https://blog.youkuaiyun.com/PerfectW_1230/article/details/41978635PerfectW_1230Wed, 17 Dec 2014 10:30:51 +0800https://blog.youkuaiyun.com/PerfectW_1230/article/details/41956393https://blog.youkuaiyun.com/PerfectW_1230/article/details/41956393PerfectW_1230Tue, 16 Dec 2014 09:43:38 +0800https://blog.youkuaiyun.com/PerfectW_1230/article/details/41941873https://blog.youkuaiyun.com/PerfectW_1230/article/details/41941873PerfectW_1230Mon, 15 Dec 2014 11:43:52 +0800https://blog.youkuaiyun.com/PerfectW_1230/article/details/41929117https://blog.youkuaiyun.com/PerfectW_1230/article/details/41929117PerfectW_1230Sun, 14 Dec 2014 21:32:00 +0800https://blog.youkuaiyun.com/PerfectW_1230/article/details/41924935https://blog.youkuaiyun.com/PerfectW_1230/article/details/41924935PerfectW_1230Sun, 14 Dec 2014 14:32:23 +0800https://blog.youkuaiyun.com/PerfectW_1230/article/details/41924071https://blog.youkuaiyun.com/PerfectW_1230/article/details/41924071PerfectW_1230Sun, 14 Dec 2014 11:57:45 +0800ARC也就是自动引用计数,是自IOS 5之后增加的新特性,编译器会在适当的地方插入适当的retaini、release、autorelease内存管理代码，完全消除了手动管理内存的繁琐。  2>ARC是OC的编译器特性，而不是IOS运行时特性，它也不类似其他语言中的垃圾回收器。就是在编译器编译代码的]]>https://blog.youkuaiyun.com/PerfectW_1230/article/details/41908983https://blog.youkuaiyun.com/PerfectW_1230/article/details/41908983PerfectW_1230Sat, 13 Dec 2014 12:16:06 +0800使用场景 我们在程序中通过alloc(new/copy)方法创建了一个对象，就必须在不使用它的时候，对它进行一次release操作。通常情况下，我们可以很明确的知道我们在何时将不再使用它，从而轻松的在某个位置手动对它进行一次release。但是有时候，]]>https://blog.youkuaiyun.com/PerfectW_1230/article/details/41907675https://blog.youkuaiyun.com/PerfectW_1230/article/details/41907675PerfectW_1230Sat, 13 Dec 2014 09:47:42 +0800