iOS NSError详解 NSError错误code对照表 自定义、定制NSError 一看就懂

一、nserror是错误信息类

//两种初始化方法：其中，domain 不能为空 dict可以为空
- (instancetype)initwithdomain:(nserrordomain)domain code:(nsinteger)code userinfo:(nullable nsdictionary *)dict;

+ (instancetype)errorwithdomain:(nserrordomain)domain code:(nsinteger)code userinfo:(nullable nsdictionary *)dict;

@property (readonly, copy) nserrordomain domain;//错误域

错误域主要有四个，对于carbon框架的error，归于osstatus domain（nsosstatuserrordomain），对于posix error，归于nsposixerrordomain，而对于我们的ios开发，一般使用nscocoaerrordomain。nserror.h定义了四个domain

{

// predefined domain for errors from most appkit and foundation apis.
foundation_export nserrordomain const nscocoaerrordomain;

// other predefined domains; value of "code" will correspond to preexisting values in these domains.
foundation_export nserrordomain const nsposixerrordomain;
foundation_export nserrordomain const nsosstatuserrordomain;
foundation_export nserrordomain const nsmacherrordomain;

}

@property (readonly) nsinteger code;//错误代码

@property (readonly, copy) nsdictionary *userinfo;//错误信息


@property (readonly, copy) nsstring *localizeddescription;//获取本地化描述


@property (nullable, readonly, copy) nsstring *localizedfailurereason;//获取失败原因


@property (nullable, readonly, copy) nsstring *localizedrecoverysuggestion;//获取恢复建议


@property (nullable, readonly, copy) nsarray *localizedrecoveryoptions;本地恢复建议


@property (nullable, readonly, strong) id recoveryattempter;


@property (nullable, readonly, copy) nsstring *helpanchor;

预定义的userinfo键名

nsstring *const nsunderlyingerrorkey;//推荐的标准方式，通用键

nsstring *const nslocalizeddescriptionkey; // 详细描述键
nsstring *const nslocalizedfailurereasonerrorkey; // 失败原因键
nsstring *const nslocalizedrecoverysuggestionerrorkey; //恢复建议键
nsstring *const nslocalizedrecoveryoptionserrorkey; // 恢复选项键

//其他键

nsstring *const nsrecoveryattemptererrorkey;
nsstring *const nshelpanchorerrorkey;

nsstring *const nsstringencodingerrorkey ;
nsstring *const nsurlerrorkey;
nsstring *const nsfilepatherrorkey;

用法示例：

nsdictionary *userinfo1 = [nsdictionary dictionarywithobjectsandkeys:@"由于文件不存在，无法打开", nslocalizeddescriptionkey, @"失败原因：文件不存在", nslocalizedfailurereasonerrorkey, @"恢复建议：请创建该文件",nslocalizedrecoverysuggestionerrorkey,nil];

nserror *error = [[nserror alloc] initwithdomain:nscocoaerrordomain code:4 userinfo:userinfo1];//此处code是4，对照下面对照表4代表文件不存在。userinfo传userinfo1 查看自定义打印。userinfo传nil，查看本地化描述。

nslog(@"========%@",[error localizeddescription]);
nslog(@"========%@",[error localizedfailurereason]);
nslog(@"========%@",[error localizedrecoverysuggestion]);

二、nserror错误code对照表

foundation constants reference
nserror codes

nserror codes in the cocoa error domain.

enum {
nsfilenosuchfileerror = 4,
nsfilelockingerror = 255,
nsfilereadunknownerror = 256,
nsfilereadnopermissionerror = 257,
nsfilereadinvalidfilenameerror = 258,
nsfilereadcorruptfileerror = 259,
nsfilereadnosuchfileerror = 260,
nsfilereadinapplicablestringencodingerror = 261,
nsfilereadunsupportedschemeerror = 262,
nsfilereadtoolargeerror = 263,
nsfilereadunknownstringencodingerror = 264,
nsfilewriteunknownerror = 512,
nsfilewritenopermissionerror = 513,
nsfilewriteinvalidfilenameerror = 514,
nsfilewriteinapplicablestringencodingerror = 517,
nsfilewriteunsupportedschemeerror = 518,
nsfilewriteoutofspaceerror = 640,
nsfilewritevolumereadonlyerror = 642m
nskeyvaluevalidationerror = 1024,
nsformattingerror = 2048,
nsusercancellederror = 3072,

nsfileerrorminimum = 0,
nsfileerrormaximum = 1023,
nsvalidationerrorminimum = 1024,
nsvalidationerrormaximum = 2047,
nsformattingerrorminimum = 2048,
nsformattingerrormaximum = 2559,

nspropertylistreadcorrupterror = 3840,
nspropertylistreadunknownversionerror = 3841,
nspropertylistreadstreamerror = 3842,
nspropertylistwritestreamerror = 3851,
nspropertylisterrorminimum = 3840,
nspropertylisterrormaximum = 4095

nsexecutableerrorminimum = 3584,
nsexecutablenotloadableerror = 3584,
nsexecutablearchitecturemismatcherror = 3585,
nsexecutableruntimemismatcherror = 3586,
nsexecutableloaderror = 3587,
nsexecutablelinkerror = 3588,
nsexecutableerrormaximum = 3839,

}
url loading system error codes

these values are returned as the error code property of an nserror object with the domain “nsurlerrordomain”.

typedef enum
{
nsurlerrorunknown = -1,
nsurlerrorcancelled = -999,
nsurlerrorbadurl = -1000,
nsurlerrortimedout = -1001,
nsurlerrorunsupportedurl = -1002,
nsurlerrorcannotfindhost = -1003,
nsurlerrorcannotconnecttohost = -1004,
nsurlerrordatalengthexceedsmaximum = -1103,
nsurlerrornetworkconnectionlost = -1005,
nsurlerrordnslookupfailed = -1006,
nsurlerrorhttptoomanyredirects = -1007,
nsurlerrorresourceunavailable = -1008,
nsurlerrornotconnectedtointernet = -1009,
nsurlerrorredirecttononexistentlocation = -1010,
nsurlerrorbadserverresponse = -1011,
nsurlerrorusercancelledauthentication = -1012,
nsurlerroruserauthenticationrequired = -1013,
nsurlerrorzerobyteresource = -1014,
nsurlerrorcannotdecoderawdata = -1015,
nsurlerrorcannotdecodecontentdata = -1016,
nsurlerrorcannotparseresponse = -1017,
nsurlerrorfiledoesnotexist = -1100,
nsurlerrorfileisdirectory = -1101,
nsurlerrornopermissionstoreadfile = -1102,
nsurlerrorsecureconnectionfailed = -1200,
nsurlerrorservercertificatehasbaddate = -1201,
nsurlerrorservercertificateuntrusted = -1202,
nsurlerrorservercertificatehasunknownroot = -1203,
nsurlerrorservercertificatenotyetvalid = -1204,
nsurlerrorclientcertificaterejected = -1205,
nsurlerrorclientcertificaterequired = -1206,
nsurlerrorcannotloadfromnetwork = -2000,
nsurlerrorcannotcreatefile = -3000,
nsurlerrorcannotopenfile = -3001,
nsurlerrorcannotclosefile = -3002,
nsurlerrorcannotwritetofile = -3003,
nsurlerrorcannotremovefile = -3004,
nsurlerrorcannotmovefile = -3005,
nsurlerrordownloaddecodingfailedmidstream = -3006,
nsurlerrordownloaddecodingfailedtocomplete = -3007
}

三、自定义nserror

系统的nserror是可以自己定制的，以下提供代码来实现并表示如何使用：

yxerror.h 与yxerror.m

//
//  yxerror.h
//  customyxerror
//
//  copyright (c) 2014年 y.x. all rights reserved.
//

#import 

// 自行添加错误码
typedef enum : nsuinteger {
  crash		= -10000,
  disconnect,
  unknow,
} yxerrorcode;

@interface yxerror : nsobject

+ (nserror *)errorcode:(yxerrorcode)code userinfo:(nsdictionary *)dic;
+ (nsstring *)transformcodetostringinfo:(yxerrorcode)code;

@end

//
//  yxerror.m
//  customyxerror
//
//  copyright (c) 2014年 y.x. all rights reserved.
//

#import "yxerror.h"

static nsdictionary *errordictionary = nil;

@implementation yxerror

+ (void)initialize
{
    if (self == [yxerror class])
    {
        errordictionary = \
        @{
          /* code        :        errorwithdomain */
          /* ==================================== */
          
          @(crash)       :        @"crash",
          @(disconnect)  :        @"disconnect",
          @(unknow)      :        @"unknow",
          
          /* ==================================== */
          };
    }
}

+ (nserror *)errorcode:(yxerrorcode)code userinfo:(nsdictionary *)dic
{
    return [nserror errorwithdomain:errordictionary[@(code)]
                               code:code
                           userinfo:dic];
}

+ (nsstring *)transformcodetostringinfo:(yxerrorcode)code
{
    return errordictionary[@(code)];
}

@end

以下是使用的代码：

//
//  appdelegate.m
//  nserror
//
//  copyright (c) 2014年 youxianming. all rights reserved.
//

#import "appdelegate.h"
#import "yxerror.h"

@implementation appdelegate

- (bool)application:(uiapplication *)application didfinishlaunchingwithoptions:(nsdictionary *)launchoptions
{
    // 定制一个nserror
    nserror *error = [yxerror errorcode:crash
      userinfo:nil];
    nslog(@"%@", error);
    
    // 翻译一个nserror（将code值翻译成字符串）
    nslog(@"%@", [yxerror transformcodetostringinfo:-10000]);
    
    return yes;
}

@end