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"];