iOS catches exceptions, common exception handling methods.

Preface: When developing an app, we usually need to catch exceptions, prevent the application from suddenly crashing, and prevent users from being unfriendly. In fact, object-c exception handling methods and Java similarities, understand the Java friends A look on the understanding. Why should I write this blog post? Because I found that the introduction of Baidu, a lot of it is not what I want, and I want to say it is not clear, the point is that we are directly copy other people's Code ... So not much to say, we look down ~ ~ ~

The following programs have been tested and passed:

Device: in IOS8 simulator

Development tools: XCode6.1

Catch exceptions using @try, catch:

Here's the simplest code notation, where @finally can get rid of:

@try {    //  may appear crash code }@catch (nsexception *exception) {     // the caught exception exception }@finally  {    //  result processing }

Here's a more detailed way to throw an exception:

@try {//1[self trytwo];} @catch (NSException*exception) {    //2NSLog (@"%s\n%@", __function__, exception);//@throw exception;//you can't throw an exception here .} @finally {//3NSLog (@"I'm sure I'll do it .");}//4//This is going to be done .NSLog (@"Try");

Trytwo Method Code:

- (void) trytwo{@try {//5NSString *str =@"ABC"; [Str substringfromindex:111];//The program will collapse here .} @catch (NSException*exception) {        //6//@throw exception;//throws an exception, which is handled by the top level//7NSLog (@"%s\n%@", __function__, exception); } @finally {//8NSLog (@"Trytwo-I'm sure I'll do it ."); }        //9//If an exception is thrown, then this code does not executeNSLog (@"If an exception is thrown here, then this code will not execute");}

For your convenience, let me explain the situation here:

If 6 throws an exception, then the order of execution is:1,5,6 , 8, 3, 4 If 6 does not throw an exception, then the order of execution is:1,5,7, 8, 9, 3-4

2) Part of the collapse of the situation we are unavoidable, even QQ will have a crash. So we can do some "action" (Collect the error message) before the program crashes, the following example is to send the caught exception to the developer's mailbox.

Appdelegate.m

-(BOOL) Application: (UIApplication *) application didfinishlaunchingwithoptions: (Nsdictionary *) launchoptions {//Override point for customization after application launch.Nssetuncaughtexceptionhandler (&Uncaughtexceptionhandler); returnYES;}voidUncaughtexceptionhandler (NSException *exception) {    /** * Get exception crash information*/Nsarray*callstack =[Exception callstacksymbols]; NSString*reason =[Exception reason]; NSString*name =[exception name]; NSString*content = [NSString stringWithFormat:@"======== Exception error report ========\nname:%@\nreason:\n%@\ncallstacksymbols:\n%@", Name,reason,[callstack componentsjoinedbystring:@"\ n"]]; /** * Send abnormal crash information to developer email*/nsmutablestring*mailurl = [nsmutablestringstring]; [Mailurl appendString:@"Mailto:[email protected]"]; [Mailurl appendString:@"subject= program Abnormal crash, please cooperate with send exception report, thank you for your cooperation! "]; [Mailurl AppendFormat:@"&body=%@", content]; //Open AddressNSString *mailpath =[Mailurl stringbyaddingpercentescapesusingencoding:nsutf8stringencoding]; [[UIApplication sharedapplication] Openurl:[nsurl urlwithstring:mailpath];}

To send a message, see my other blog post:

iOS Development-Send email (e-mail) method to organize the collection (total 3 kinds)

Blog Garveycalvin

Blog Source: http://www.cnblogs.com/GarveyCalvin/

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iOS catches exceptions, common exception handling methods.