*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