问题： 为什么会崩溃？2017-12-19 15:09:25.923 HookNetwork2[4030:501650] *** NSForwarding: warning: selector (0x60000000e020) for message 'X?ü' does not match selector known to Objective C runtime (0x608000004340)-- abort
2017-12-19 15:09:25.924 HookNetwork2[4030:501650] (null): unrecognized selector sent to instance 0x60000000dea0
2017-12-19 15:09:25.928 HookNetwork2[4030:501650] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '(null): unrecognized selector sent to instance 0x60000000dea0'
*** First throw call stack:
(
0 CoreFoundation 0x000000010926fb0b __exceptionPreprocess + 171
1 libobjc.A.dylib 0x0000000108cd4141 objc_exception_throw + 48
2 CoreFoundation 0x00000001092df134 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
3 CoreFoundation 0x00000001091f6840 ___forwarding___ + 1024
4 CoreFoundation 0x00000001091f63b8 _CF_forwarding_prep_0 + 120
5 HookNetwork2 0x00000001086fc379 __20+[RAObserverer load]_block_invoke_2 + 153
6 HookNetwork2 0x00000001086fd6a3 -[ViewController connectTest:] + 1731
7 UIKit 0x0000000109694d82 -[UIApplication sendAction:to:from:forEvent:] + 83
8 UIKit 0x00000001098195ac -[UIControl sendAction:to:forEvent:] + 67
9 UIKit 0x00000001098198c7 -[UIControl _sendActionsForEvents:withEvent:] + 450
10 UIKit 0x0000000109818802 -[UIControl touchesEnded:withEvent:] + 618
11 UIKit 0x00000001097027ea -[UIWindow _sendTouchesForEvent:] + 2707
12 UIKit 0x0000000109703f00 -[UIWindow sendEvent:] + 4114
13 UIKit 0x00000001096b0a84 -[UIApplication sendEvent:] + 352
14 UIKit 0x0000000109e945d4 __dispatchPreprocessedEventFromEventQueue + 2926
15 UIKit 0x0000000109e8c532 __handleEventQueue + 1122
16 CoreFoundation 0x0000000109215c01 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
17 CoreFoundation 0x00000001091fb0cf __CFRunLoopDoSources0 + 527
18 CoreFoundation 0x00000001091fa5ff __CFRunLoopRun + 911
19 CoreFoundation 0x00000001091fa016 CFRunLoopRunSpecific + 406
20 GraphicsServices 0x000000010d044a24 GSEventRunModal + 62
21 UIKit 0x0000000109693134 UIApplicationMain + 159
22 HookNetwork2 0x00000001086ff2bf main + 111
23 libdyld.dylib 0x000000010c0d965d start + 1
24 ??? 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
前面的代码哪里有问题，为什么断点信息是这样的？
这里有一个crash demo，可以下载下来看一看。
遇到问题找不到原因时可以多看看官方文档，说不定会有思路。
解决方案2:那个RAObserverer是什么东西？代码里没有，奔溃调用栈里看起来跟上面代码没关系。
需要知道这两句是干了什么,从调用栈看是RAObserverer没有load方法的实现
5 HookNetwork2 0x00000001086fc379 __20+[RAObserverer load]_block_invoke_2 + 153
6 HookNetwork2 0x00000001086fd6a3 -[ViewController connectTest:] + 1731关键：imp_implementationWithBlock这个block的参数里是没有SEL的
解决方案3:建议阅读一下imp_implementationWithBlock的文档。
Parameters
block
The block that implements this method. The signature of block should be method_return_type ^(id self, self, method_args …). The selector of the method is not available to block. block is copied with Block_copy().
你的代码里面的block的类型里面是需要了一个seletor, 打断点的得知，此时swizzle selector的值是一个NSURLRequest，明显不是我们想要的selector，所以objc_msgSend就失败了。
查阅文档可知，block的签名应该是method_return_type ^(id self, self, method_args …).是不需要SEL的，所以将上述的代码改为：
id swizzleBlock = ^(NSURLConnection *slf, NSURLRequest *request,id delegate) {
return ((NSURLConnection*(*)(NSURLConnection*,SEL,NSURLRequest*,id))objc_msgSend)(slf,swizzledSelector,request,delegate);
};
运行可以成功，点击按钮也OK了。