IOS exception Handling (-)

In the development process, often to use exception handling, to prevent the sudden collapse of the program, in the java,c++ throw exception, and assertion processing, then in OC is how to deal with the exception?

1. Nsassert

See how iOS is defined

#if !defined (_nsassertbody)#define Nsassert (condition, desc, ...)         Do {                    __pragma_push_no_extra_arg_warnings     if (!  (condition)) {[                [Nsassertionhandler Currenthandler] handlefailureinmethod:_cmd         object: Self file: [NSString stringwithutf8string:__file__]             LINENUMBER:__LINE__ Description: (DESC), # #__VA_ARGS__];     }                        __pragma_pop_no_extra_arg_warnings     while (0)#endif 

Specific usage:

If condition is false, throws an exception

    int 0 ;    Nsassert (a! =0,@ "x must not being zero", __func__);

Exception information thrown:

£ º47.692 audiodemo[1928   in-[gnviewcontroller touchesbegan:withevent:],/users/geng/desktop/programe/audio/audiodemo/ AUDIODEMO/GNVIEWCONTROLLER.M:

2. Since Nsassert references self, it is easy to cause circular references at block time, so it is common to use the following assertion

#define Nscassert (condition, desc, ...)      Do {                    __pragma_push_no_extra_arg_warnings     if (!  (condition)) {[                [Nsassertionhandler Currenthandler] handlefailureinfunction:[nsstring stringwithutf8string:__pretty_ FUNCTION__]         file:[nsstring stringwithutf8string:__file__]             linenumber:__line__ Description: (DESC), # #__VA _ARGS__];     }                        __pragma_pop_no_extra_arg_warnings     while (0)

3.throw Throw exception

    // Throw Exception    if Ten {        nsexception* exp = [nsexception exceptionwithname:@ "num >" Reason: @" num > Ten " Userinfo:nil];         @throw exp;    }

The printing results are:

 -- One- +  -: +:33.999exceptiondemo[2136: 60b]4 -- One- +  -: +:34.296exceptiondemo[2136: 60b]5 -- One- +  -: +:34.775exceptiondemo[2136: 60b]6 -- One- +  -: +:35.254exceptiondemo[2136: 60b]7 -- One- +  -: +:35.813exceptiondemo[2136: 60b]8 -- One- +  -: +:36.429exceptiondemo[2136: 60b]9 -- One- +  -: +:36.983exceptiondemo[2136: 60b]Ten -- One- +  -: +:37.597exceptiondemo[2136: 60b] * * * terminating app due to uncaught exception'num > Ten', Reason:'num > Ten'FirstThrowCall stack: (0Corefoundation0x017ec1e4__exceptio

This is a direct crash, if you want to not crash, continue to execute, then you need to use a try Catch

    @try {         [self.mybox Pushin];    }     @catch (NSException *exception) {        NSLog (@ "%@", Exception.reason);    }     @finally  {        [Self.mybox printnumber];    }

This will not break down.

IOS exception Handling (-)