JSPatch学习笔记
本文参考JSPatch wiki :https://github.com/bang590/JSPatch/wiki
1.概念
JSPatch是一个轻量的JS引擎,能够使用JavaScript语言来调用任何object-c接口,替换任何原生的方法。目前主要用于发步JS脚本替换原生Objective-C代码,实时修复线上bug
2.原理
利用OC语言的动态性,动态的修改类的方法和属性。在app启动的时候加载我们写好的JavaScript文件并通过JavaScriptCore来执行,用JS写好的类函数去篡改原有的OC函数。JSPatch只提供了篡改这个过程的代码,像部署线上Js代码、下载这些逻辑都得自己写。当然你可以用JSpatchSDK这个平台,这个平台帮我们部署JS代码、下载等一些逻辑。JSPatchSDK是收费的,也有免费版的。
3.部署
通过pod或者其他方式引入JSPatch,在didFinishLaunchingWithOptions函数加上如下代码:
[JPEngine startEngine]; NSString *sourcePath = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"js"]; NSString *script = [NSString stringWithContentsOfFile:sourcePath encoding:NSUTF8StringEncoding error:nil]; [JPEngine evaluateScript:script];
部署完OC代码,我们就可以在index.js专心写JavaScript来修复线上的bug.
4.写JS代码
- defineClass 用来定义(覆盖)一个类
-
defineClass(classDeclaration, [properties,] instanceMethods, classMethods) classDeclaration:字符串类型,代表类名字 properties:一个字符串数组,代表要添加的属性列表 instanceMethods:实例方法 classMethods:累方法
- 下面是一个例子:
- 包含了22个知识点,学会了这22个点,就能完成JSPatch的大部分工作了
- 如果还有不明白的地方可以看官网
- 1.appDelegate.m文件
-
[JPEngine startEngine]; NSString *sourcePath = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"js"]; NSString *script = [NSString stringWithContentsOfFile:sourcePath encoding:NSUTF8StringEncoding error:nil]; [JPEngine evaluateScript:script]; self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen] bounds]]; UINavigationController * navi = [[UINavigationController alloc]initWithRootViewController:[[MainViewController alloc]initWithNibName:@"MainViewController" bundle:nil]]; self.window.rootViewController = navi; [self.window makeKeyAndVisible];
- 2.MainViewController.h
-
// // MainViewController.h // JSPatchDemo // // Created by 朱国清 on 16/12/23. // Copyright © 2016年 bang. All rights reserved. // #import <UIKit/UIKit.h> @interface MainViewController : UIViewController @property (nonatomic,strong) NSArray * testArray; @property (nonatomic,strong) NSDictionary * testDictionary; @end
- 3.MainViewController.m
-
// // MainViewController.m // JSPatchDemo // // Created by 朱国清 on 16/12/23. // Copyright © 2016年 bang. All rights reserved. // #import "MainViewController.h" @interface MainViewController () @property NSString * privateKey; @end @implementation MainViewController - (void)viewDidLoad { [super viewDidLoad]; self.testArray = @[@"Apple",@"Boy",@"Cat",@"Dog",]; self.testDictionary = @{@"name":@"jack",@"age":@20}; self.privateKey = @"i am a private key"; [self initUI]; } // js 覆盖 -(void)initUI{ if (false) { UIButton * btn = [[UIButton alloc]initWithFrame:CGRectMake(10,30, 100, 30)]; [btn setTitle:@"go" forState:UIControlStateNormal]; [btn setBackgroundColor:[UIColor brownColor]]; [btn addTarget:self action:@selector(handleButton) forControlEvents:UIControlEventTouchUpInside]; } } -(void)handleButton{ } -(void)testString:(NSString *)string{ NSLog(@"testString : %@",string); } - (void)testPointer:(NSError **)error { NSError *err = [[NSError alloc]initWithDomain:@"com.jspatch" code:42 userInfo:nil]; *error = err; } -(void)request:(void(^)(NSString *content, BOOL success))callback { callback(@"I'm content", YES); } typedef void (^JSBlock)(NSString *str); -(JSBlock)getBlock{ JSBlock block = ^(NSString *str) { NSLog(@"I'm %@",str); }; return block; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; } @end
- 4.index.js
-
defineClass( 'MainViewController', { viewWillAppear:function(animated){ // 1.调用父类 self.super() self.super().viewWillAppear(animated); // 2.设置navigationBarHidden属性值 .setNavigationBarHidden(true) self.navigationController().setNavigationBarHidden(true); }, initUI:function(){ // 3.oc的NSString对象,在JS里面是Object // 4.privateKey 为私有属性 var privateKey = self.valueForKey("privateKey"); self.testString(privateKey); console.log('privateKey:'+ privateKey); // 5.OC NSArray var item1 = self.testArray().objectAtIndex(0); console.log('item1:'+item1.toString()); // 6.OC NSArray => JS array var jsArray = self.testArray().toJS(); console.log('jsArray[0]:'+jsArray[0]); // 7.OC NSDictionary var name1 = self.testDictionary().valueForKey('name'); console.log('name1:'+name1); // 8.OC NSDictionary => JS json var dic = self.testDictionary().toJS(); console.log('name2:'+dic['name']); // 10.获取属性 self.view() // 11.获取一个类 require('UIColor') self.view().setBackgroundColor(require('UIColor').grayColor()); /* 12. 特殊变量 point {x:, y: } size {width:, height:} CGRect {x:, y:, width:, height:} range {location:, length:} */ var btn = require('UIButton').alloc().initWithFrame({x:20, y:30, width:100, height:30}); btn.setBackgroundColor(UIColor.brownColor()); // 13.多参数函数 [btn setTitle:forState:];以_代替: btn.setTitle_forState() btn.setTitle_forState('go',0); // 14.Selector 用字符代替 btn.addTarget_action_forControlEvents(self,'handlePress',1 << 6); self.view().addSubview(btn); // 15.block无法使用self,需要保存一下 var slf = self; // 16. // 弱引用 var weakSelf = __weak(self) // 强引用 var strongSelf = __strong(self) // 17. block // block block的参数类型用字符串标示,block对象用NSBlock*类型 /* 从 JS 传 block 到 OC,有两个限制: A. block 参数个数最多支持6个。(若需要支持更多,可以修改源码) B. block 参数类型不能是 double / NSBlock / struct 类型。 */ self.request(block("NSString *, BOOL", function(ctn, succ) { if (succ) console.log(ctn) //output: I'm content slf.testString("block self"); })); // 18. oc 返回的block就是一个js函数,可以直接调用 slf.getBlock()('JavaScrict'); // 19.GCD // JS dispatch_after(1.0, function(){ console.log('dispatch_after 1s'); }) dispatch_async_main(function(){ console.log('dispatch_async_main'); }) dispatch_sync_main(function(){ console.log('dispatch_sync_main'); }) dispatch_async_global_queue(function(){ console.log('dispatch_async_global_queue'); }) // 20.参入id * 指针 //malloc() pval() free() is provided by JPMemory extension require('JPEngine').addExtensions(['JPMemory']) var pError = malloc(sizeof("id")) self.testPointer(pError) var error = pval(pError) if (!error) { console.log("success") } else { console.log(error) } releaseTmpObj(pError) free(pError) }, handlePress:function(){ console.log('handlePress'); var vc = InfoViewController.alloc().init(); self.navigationController().pushViewController_animated(vc,true); } } ) // 21.定义一个继承 UIViewController的类 // 22.定义两个属性 url、info defineClass('InfoViewController : UIViewController', [ 'url', 'info', ], { viewDidLoad:function(){ self.super().viewDidLoad(); self.navigationController().setNavigationBarHidden(false); self.view().setBackgroundColor(require('UIColor').whiteColor()); self.setUrl('www.pingan.com.cn'); console.log(self.url()); } } );