20160126深入浅出obc知识点整理

1.错误域Error Domain

NSMachErrorDomain:系统内核错误

NSPOSIXErrorDomain:系统错误

NSOSStatusErrorDomian:MacOS9之前的错误或者Carbon框架错误

NSCocoaErrorDomain:cocoa框架错误

 

2.本地化错误描述

(1)NSUnderlyingErrorKey

NSDictionary *userInfo = [error userInfo];

NSString *errorDesc = nil;

 

//检查有没有"NSUnderlyingErrorKey"可供使用

if(userInfo && [userInfo objectForKey:NSUnderlyingErrorKey]){

     NSError *underlyingError = [userInfo objectForKey:NSUnderlyingErrorKey];

     if(underlyingError){

          errorDesc = [underlyingError localizedDescription];

     }

     else{

          errorDesc = [error localizedDescription];

     }

}

else{

    errorDesc = [error localizedDescription];

}

 

(2)localized Description

NSError *errorInfo = nil;

//假设在操作系统的根目录上放一个"test.rtf"文件,strTest拿到@"/test.rf"的内容

NSString *strTest = [NSString stringWithContentsOfFile:@"/test.rf"

                                             encoding:NSUTF8StringEncoding

                                             ettor:&errorInfo];

 

if(!strTest){

    if(!errorInfo){

       NSLog(@"An error occurred: %@" , [errorInfo localizedDescription]);

    }else{

       NSLog(@"An unknow error occurred" );

    }

}

 

3.输出当前的函数

%s __FUNCTION__

 

4.单例

share*****

default*****

 

5.ARC

weak和strong代替assign.retain.copy

 

6.KVC

valueForKeyPath  取

setValue: forkey:  设置

 

7.KVO

[self addObserver:self

        forKeyPath:@"datasrc"

        options:*****

        context:@"testContent"];