diff --git a/Chapter1 - iOS/1.81.md b/Chapter1 - iOS/1.81.md
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+# __asm__ 重命名符号
+
+> 最近看到 __asm__ ，所以在自己简单实验下，有了本文。
+
+
+## 探索
+
+1. 实验1
+```c
+#import <Foundation/Foundation.h>【爬sw
+
+int age __asm__("objc_age") = 25;
+
+void foo(void) __asm__("@杭城小刘");
+void foo (void) {
+    printf("Hello world\n");
+}
+
+int main(int argc, const char * argv[]) {
+    foo();
+    return 0;
+}
+```
+
+在 foo 方法里面下断点，见下图
+
+![rename symbol](https://raw.githubusercontent.com/FantasticLBP/knowledge-kit/master/assets/2020-02-25-asm.png)
+
+可以看到，`foo` 方法的 symbol 被变为 `@杭城小刘`，变量 `age` 被变为 `objc_age`。
+
+2. 实验2
+```objective-c
+#import "AppDelegate.h"
+
+int main(int argc, char * argv[]) __asm__("mook_main");
+int main(int argc, char * argv[]) {
+    NSString * appDelegateClassName;
+    @autoreleasepool {
+        // Setup code that might create autoreleased objects goes here.
+        appDelegateClassName = NSStringFromClass([AppDelegate class]);
+    }
+    return UIApplicationMain(argc, argv, nil, appDelegateClassName);
+}
+```
+
+![App main 方法 rename 失败](https://raw.githubusercontent.com/FantasticLBP/knowledge-kit/master/assets/2020-02-25-asm2.png)
+
+可以看到 App 工程主入口函数 `main` 函数，想修改为 `mook_main`。但是报错 `ld: entry point (_main) undefined. fir architecture x86_64`
+
+当把 `main` 函数修改为 `_main` 发现成功。
+
+
+
+
+## 应用
+
+鉴于 __asm__ 可以修改 symbol 名称，那么我们可以给工程做混淆。
+
+等待深入研究后继续更新...
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diff --git a/Chapter1 - iOS/chapter1.md b/Chapter1 - iOS/chapter1.md
index 560af97..c37cf70 100644
--- a/Chapter1 - iOS/chapter1.md	
+++ b/Chapter1 - iOS/chapter1.md	
@@ -83,4 +83,6 @@
   * [77、iOS 打包系统构建加速](https://github.com/FantasticLBP/knowledge-kit/blob/master/Chapter1%20-%20iOS/1.77.md)
   * [78、上架包预检](https://github.com/FantasticLBP/knowledge-kit/blob/master/Chapter1%20-%20iOS/1.78.md)
   * [79、深入理解各种锁](https://github.com/FantasticLBP/knowledge-kit/blob/master/Chapter1%20-%20iOS/1.79.md)
-  * [80、打造功能强大的数据上报组件](https://github.com/FantasticLBP/knowledge-kit/blob/master/Chapter1%20-%20iOS/1.80.md)
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+  * [80、打造功能强大的数据上报组件](https://github.com/FantasticLBP/knowledge-kit/blob/master/Chapter1%20-%20iOS/1.80.md)
+  * [81、__asm__ 重命名符号](https://github.com/FantasticLBP/knowledge-kit/blob/master/Chapter1%20-%20iOS/1.81.md)
+  
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