链接错误

Undefined symbols

只声明了符号，却未定义符号的具体实现。
分两种情况
1、符号没有具体实现。 2、符号有具体实现，但是链接器并不知道具体实现在哪。

对于第1种情况，需要实现符号定义。

对于第2种情况，我们只有配置好链接就好了。

常见的链接错误情况

libc++

错误形式如下：

Undefined symbols for architecture x86_64:   "vtable for __cxxabiv1::__class_type_info", referenced from:       typeinfo for FireflyTLV::TLVEntity in FireflyCrypto(TLVPackage.o)   NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.   "std::__1::__shared_weak_count::~__shared_weak_count()", referenced from:       std::__1::__shared_ptr_pointer<FireflyTLV::TLVEntity*, std::__1::default_delete<FireflyTLV::TLVEntity>, std::__1::allocator<FireflyTLV::TLVEntity> >::~__shared_ptr_pointer() in FireflyCrypto(TLVPackage.o)       std::__1::__shared_ptr_pointer<FireflyTLV::TLVEntity*, std::__1::default_delete<FireflyTLV::TLVEntity>, std::__1::allocator<FireflyTLV::TLVEntity> >::~__shared_ptr_pointer() in FireflyCrypto(TLVPackage.o)   "_inflate", referenced from:       _unzReadCurrentFile in Minizip(unzip.o)

libz 和 libz2

错误形式如下：

Undefined symbols for architecture x86_64:   "_inflate", referenced from:       _unzReadCurrentFile in Minizip(unzip.o)   "_inflateInit2_", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)   "_get_crc_table", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)       _zipOpenNewFileInZip3 in Minizip(zip.o)   "_inflateEnd", referenced from:       _unzCloseCurrentFile in Minizip(unzip.o)   "_BZ2_bzReadOpen", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o)   "_BZ2_bzRead", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o)

libsqlite3

错误形式如下：

Undefined symbols for architecture x86_64:   "_sqlite3_column_bytes", referenced from:       -[FMResultSet dataForColumnIndex:] in FMDB(FMResultSet.o)       -[FMResultSet dataNoCopyForColumnIndex:] in FMDB(FMResultSet.o)   "_sqlite3_column_double", referenced from:       -[FMResultSet doubleForColumnIndex:] in FMDB(FMResultSet.o)   "_sqlite3_column_int", referenced from:       -[FMResultSet intForColumnIndex:] in FMDB(FMResultSet.o)   "_sqlite3_column_text", referenced from:       -[FMResultSet kvcMagic:] in FMDB(FMResultSet.o)       -[FMResultSet stringForColumnIndex:] in FMDB(FMResultSet.o)       -[FMResultSet UTF8StringForColumnIndex:] in FMDB(FMResultSet.o)   "_sqlite3_column_name", referenced from:       -[FMResultSet columnNameToIndexMap] in FMDB(FMResultSet.o)       -[FMResultSet kvcMagic:] in FMDB(FMResultSet.o)       -[FMResultSet resultDictionary] in FMDB(FMResultSet.o)       -[FMResultSet columnNameForIndex:] in FMDB(FMResultSet.o)   "_sqlite3_column_count", referenced from:       -[FMResultSet columnCount] in FMDB(FMResultSet.o)       -[FMResultSet columnNameToIndexMap] in FMDB(FMResultSet.o)       -[FMResultSet kvcMagic:] in FMDB(FMResultSet.o)       -[FMResultSet resultDictionary] in FMDB(FMResultSet.o)       -[FMResultSet stringForColumnIndex:] in FMDB(FMResultSet.o)       -[FMResultSet dateForColumnIndex:] in FMDB(FMResultSet.o)       -[FMResultSet dataForColumnIndex:] in FMDB(FMResultSet.o)       ...   "_sqlite3_result_error_code", referenced from:       -[FMDatabase resultErrorCode:context:] in FMDB(FMDatabase.o)   "_sqlite3_result_error", referenced from:       -[FMDatabase resultError:context:] in FMDB(FMDatabase.o)   "_sqlite3_result_text", referenced from:       -[FMDatabase resultString:context:] in FMDB(FMDatabase.o)   "_sqlite3_value_blob", referenced from:       -[FMDatabase valueData:] in FMDB(FMDatabase.o)   "_sqlite3_result_blob", referenced from:       -[FMDatabase resultData:context:] in FMDB(FMDatabase.o)   "_sqlite3_value_bytes", referenced from:

AssetsLibrary.framework

错误形式如下：

Undefined symbols for architecture x86_64:   "_OBJC_CLASS_$_ALAssetsLibrary", referenced from:       objc-class-ref in FireflyUI(FireflyImagePickerTool.o)

AVFoundation.framework

错误形式如下：

Undefined symbols for architecture x86_64:   "_OBJC_CLASS_$_AVAssetImageGenerator", referenced from:       objc-class-ref in FireflyUI(FireflySimpleCamera.o)   "_OBJC_CLASS_$_AVURLAsset", referenced from:       objc-class-ref in FireflyUI(FireflySimpleCamera.o)

Photos.framework

错误形式如下：

Undefined symbols for architecture x86_64:   "_OBJC_CLASS_$_PHAssetCollectionChangeRequest", referenced from:       objc-class-ref in FireflyUI(FireflyImagePickerManager.o)   "_OBJC_CLASS_$_PHImageManager", referenced from:       objc-class-ref in FireflyUI(FireflyImagePickerManager.o)   "_OBJC_CLASS_$_PHAsset", referenced from:       objc-class-ref in FireflyUI(FireflyImagePickerManager.o)   "_OBJC_CLASS_$_PHAssetCollection", referenced from:       objc-class-ref in FireflyUI(FireflyImagePickerManager.o)   "_OBJC_CLASS_$_PHFetchOptions", referenced from:       objc-class-ref in FireflyUI(FireflyImagePickerManager.o)

CoreMedia.framework

错误形式如下：

Undefined symbols for architecture x86_64:   "_CMSampleBufferGetImageBuffer", referenced from:       +[FireflyQRCodeScan imageFromSampleBuffer:] in FireflyScanCode(FireflyQRCodeScan.o)

WebKit.framework

错误形式如下：

Undefined symbols for architecture x86_64:   "_OBJC_CLASS_$_WKUserScript", referenced from:       objc-class-ref in FireflyJSBridge(FireflyWKWebView.o)   "_OBJC_CLASS_$_WKPreferences", referenced from:       objc-class-ref in FireflyJSBridge(FireflyJSWKWebViewController.o)

AddressBook.framework

错误形式如下：

Undefined symbols for architecture x86_64:   "_ABPersonCreate", referenced from:       ___65+[FireflyJSBridgePhoneContact addPhoneContact:completionHandler:]_block_invoke in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_ABAddressBookCopyArrayOfAllPeople", referenced from:       ___65+[FireflyJSBridgePhoneContact addPhoneContact:completionHandler:]_block_invoke in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_ABAddressBookRemoveRecord", referenced from:       ___65+[FireflyJSBridgePhoneContact addPhoneContact:completionHandler:]_block_invoke in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_kABPersonLastNameProperty", referenced from:       +[FireflyJSBridgePhoneContact parse:toContactPerson:] in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_kABPersonFirstNameProperty", referenced from:       +[FireflyJSBridgePhoneContact parse:toContactPerson:] in FireflyJSBridge(FireflyJSBridgePhoneContact.o)       ___65+[FireflyJSBridgePhoneContact addPhoneContact:completionHandler:]_block_invoke in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_ABPersonSetImageData", referenced from:       +[FireflyJSBridgePhoneContact parse:toContactPerson:] in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_kABPersonNicknameProperty", referenced from:       +[FireflyJSBridgePhoneContact parse:toContactPerson:] in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_kABPersonMiddleNameProperty", referenced from:       +[FireflyJSBridgePhoneContact parse:toContactPerson:] in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_kABWorkLabel", referenced from:       +[FireflyJSBridgePhoneContact parse:toContactPerson:] in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_kABPersonEmailProperty", referenced from:       +[FireflyJSBridgePhoneContact parse:toContactPerson:] in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_kABPersonOrganizationProperty", referenced from:       +[FireflyJSBridgePhoneContact parse:toContactPerson:] in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_ABRecordCopyValue", referenced from:       ___65+[FireflyJSBridgePhoneContact addPhoneContact:completionHandler:]_block_invoke in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_kABPersonAddressStateKey", referenced from:       +[FireflyJSBridgePhoneContact parse:toContactPerson:] in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_kABPersonHomePageLabel", referenced from:       +[FireflyJSBridgePhoneContact parse:toContactPerson:] in FireflyJSBridge(FireflyJSBridgePhoneContact.o)   "_CNCopyCurrentNetworkInfo", referenced from:       +[FireflyNetworkReachInfo getWifiName] in FireflyNetwork(FireflyNetworkReachInfo.o)

CoreLocation.framework

错误形式如下：

Undefined symbols for architecture x86_64:   "_OBJC_CLASS_$_CLLocationManager", referenced from:       objc-class-ref in FireflyUtil(FireflyLocationManager.o)   "_kCLLocationAccuracyBest", referenced from:       -[FireflyLocationManager startLocation] in FireflyUtil(FireflyLocationManager.o)   "_CLLocationCoordinate2DMake", referenced from:       _S_FireflyLocationManager_GetCurrentCoordinate in FireflyUtil(FireflyLocationManager.o)

SystemConfiguration.framework

错误形式如下：

Undefined symbols for architecture x86_64:   "_inflate", referenced from:       _unzReadCurrentFile in Minizip(unzip.o)   "_inflateInit2_", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)   "_get_crc_table", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)       _zipOpenNewFileInZip3 in Minizip(zip.o)   "_inflateEnd", referenced from:       _unzCloseCurrentFile in Minizip(unzip.o)   "_BZ2_bzReadOpen", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o)   "_BZ2_bzRead", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o) 0

AdSupport.framework

错误形式如下：

Undefined symbols for architecture x86_64:   "_inflate", referenced from:       _unzReadCurrentFile in Minizip(unzip.o)   "_inflateInit2_", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)   "_get_crc_table", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)       _zipOpenNewFileInZip3 in Minizip(zip.o)   "_inflateEnd", referenced from:       _unzCloseCurrentFile in Minizip(unzip.o)   "_BZ2_bzReadOpen", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o)   "_BZ2_bzRead", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o) 1

CoreTelephony.framework

错误形式如下：

Undefined symbols for architecture x86_64:   "_inflate", referenced from:       _unzReadCurrentFile in Minizip(unzip.o)   "_inflateInit2_", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)   "_get_crc_table", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)       _zipOpenNewFileInZip3 in Minizip(zip.o)   "_inflateEnd", referenced from:       _unzCloseCurrentFile in Minizip(unzip.o)   "_BZ2_bzReadOpen", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o)   "_BZ2_bzRead", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o) 2

QuickLook.framework

错误形式如下：

Undefined symbols for architecture x86_64:   "_inflate", referenced from:       _unzReadCurrentFile in Minizip(unzip.o)   "_inflateInit2_", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)   "_get_crc_table", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)       _zipOpenNewFileInZip3 in Minizip(zip.o)   "_inflateEnd", referenced from:       _unzCloseCurrentFile in Minizip(unzip.o)   "_BZ2_bzReadOpen", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o)   "_BZ2_bzRead", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o) 3

运行错误

unrecognized selector sent to instance

通常，实例instance没有响应selector，也可以说实例instance没有实现方法selector。其错误栈信息形式如下：

Undefined symbols for architecture x86_64:   "_inflate", referenced from:       _unzReadCurrentFile in Minizip(unzip.o)   "_inflateInit2_", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)   "_get_crc_table", referenced from:       _unzOpenCurrentFile3 in Minizip(unzip.o)       _zipOpenNewFileInZip3 in Minizip(zip.o)   "_inflateEnd", referenced from:       _unzCloseCurrentFile in Minizip(unzip.o)   "_BZ2_bzReadOpen", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o)   "_BZ2_bzRead", referenced from:       _ff_bs43patch in FireflyUtil(bsdiff43.o) 4

引起这个崩溃的常见情况有两个： 1、在代码中以Catagory的形式实现了对应方法，编译打包都没有问题，但是运行是没有加载Catagory方法的符号，导致崩溃。
这种情况，需要在Build Settings -> Linking -> Other Link Flags添加-ObjC