Ios 为什么链接libsqlite3.dylib和libsqlcipher.a时不发生重复符号错误？

根据本教程，我正在将sqlcipher集成到iOS项目中： 有一个热门提示是：如果libsqlite3.dylib或另一个SQLite框架在“链接二进制文件与库”列表中列出，请确保将其删除，否则您将看到重复的符号错误。
但是我尝试将libsqlite3.tbd（在xcode 7中没有动态库）和libsqlcipher.a添加到链接二进制与库，没有出现duplicate符号错误！为什么？
我注意到，如果我单击

#import

行，xcode将显示xcode的lib文件夹中的sqlite3.h文件，而不是sqlcipher中的文件。

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但是，sqlcipher确实有效，数据库是真正加密的。

libsqlite3.tbd

只是一个文本文件，它定义了库支持的平台体系结构、目标平台、动态库安装路径和导出的符号。使用

.tbd

文件，可以减小捆绑应用程序的大小，因为平台设备上已包含库二进制文件，因此不需要将其链接到应用程序映像中

---

libsqlite3.tbd

如下所示：

---
archs:           [ armv7, armv7s, arm64 ]
platform:        ios
install-name:    /usr/lib/libsqlite3.dylib
current-version: 216.4
compatibility-version: 9.0
exports:         
  - archs:           [ armv7, armv7s, arm64 ]
    symbols:         [ __sqlite3_lockstate, __sqlite3_purgeEligiblePagerCacheMemory, 
                       __sqlite3_system_busy_handler, __sqlite_auto_profile, 
                       __sqlite_auto_profile_syslog, __sqlite_auto_trace, 
                       __sqlite_auto_trace_syslog, _sqlite3OsShmHasMultipleLinks, 
                       _sqlite3OsShmRenamedWhileOpen, _sqlite3OsShmWasTruncated, 
                       _sqlite3OsShmWasUnlinkedWhileOpen, _sqlite3VersionNumber, 
                       _sqlite3VersionString, _sqlite3_aggregate_context, 
                       _sqlite3_aggregate_count, _sqlite3_auto_extension, 
                       _sqlite3_backup_finish, _sqlite3_backup_init, _sqlite3_backup_pagecount, 
                       _sqlite3_backup_remaining, _sqlite3_backup_step, 
                       _sqlite3_bind_blob, _sqlite3_bind_blob64, _sqlite3_bind_double, 
                       _sqlite3_bind_int, _sqlite3_bind_int64, _sqlite3_bind_null, 
                       _sqlite3_bind_parameter_count, _sqlite3_bind_parameter_index, 
                       _sqlite3_bind_parameter_name, _sqlite3_bind_text, 
                       _sqlite3_bind_text16, _sqlite3_bind_text64, _sqlite3_bind_value, 
                       _sqlite3_bind_zeroblob, _sqlite3_blob_bytes, _sqlite3_blob_close, 
                       _sqlite3_blob_open, _sqlite3_blob_read, _sqlite3_blob_reopen, 
                       _sqlite3_blob_write, _sqlite3_busy_handler, _sqlite3_busy_timeout, 
                       _sqlite3_cancel_auto_extension, _sqlite3_changes, 
                       _sqlite3_clear_bindings, _sqlite3_close, _sqlite3_close_v2, 
                       _sqlite3_collation_needed, _sqlite3_collation_needed16, 
                       _sqlite3_column_blob, _sqlite3_column_bytes, _sqlite3_column_bytes16, 
                       _sqlite3_column_count, _sqlite3_column_decltype, 
                       _sqlite3_column_decltype16, _sqlite3_column_double, 
                       _sqlite3_column_int, _sqlite3_column_int64, _sqlite3_column_name, 
                       _sqlite3_column_name16, _sqlite3_column_text, _sqlite3_column_text16, 
                       _sqlite3_column_type, _sqlite3_column_value, _sqlite3_commit_hook, 
                       _sqlite3_compileoption_get, _sqlite3_compileoption_used, 
                       _sqlite3_complete, _sqlite3_complete16, _sqlite3_config, 
                       _sqlite3_context_db_handle, _sqlite3_create_collation, 
                       _sqlite3_create_collation16, _sqlite3_create_collation_v2, 
                       _sqlite3_create_function, _sqlite3_create_function16, 
                       _sqlite3_create_function_v2, _sqlite3_create_module, 
                       _sqlite3_create_module_v2, _sqlite3_data_count, 
                       _sqlite3_data_directory, _sqlite3_db_config, _sqlite3_db_filename, 
                       _sqlite3_db_handle, _sqlite3_db_mutex, _sqlite3_db_readonly, 
                       _sqlite3_db_release_memory, _sqlite3_db_status, 
                       _sqlite3_declare_vtab, _sqlite3_enable_shared_cache, 
                       _sqlite3_errcode, _sqlite3_errmsg, _sqlite3_errmsg16, 
                       _sqlite3_errstr, _sqlite3_exec, _sqlite3_expired, 
                       _sqlite3_extended_errcode, _sqlite3_extended_result_codes, 
                       _sqlite3_file_control, _sqlite3_finalize, _sqlite3_free, 
                       _sqlite3_free_table, _sqlite3_get_autocommit, _sqlite3_get_auxdata, 
                       _sqlite3_get_table, _sqlite3_global_recover, _sqlite3_initialize, 
                       _sqlite3_intarray_bind, _sqlite3_intarray_create, 
                       _sqlite3_interrupt, _sqlite3_last_insert_rowid, 
                       _sqlite3_libversion, _sqlite3_libversion_number, 
                       _sqlite3_limit, _sqlite3_log, _sqlite3_malloc, _sqlite3_malloc64, 
                       _sqlite3_memory_alarm, _sqlite3_memory_highwater, 
                       _sqlite3_memory_used, _sqlite3_mprintf, _sqlite3_msize, 
                       _sqlite3_mutex_alloc, _sqlite3_mutex_enter, _sqlite3_mutex_free, 
                       _sqlite3_mutex_leave, _sqlite3_mutex_try, _sqlite3_next_stmt, 
                       _sqlite3_open, _sqlite3_open16, _sqlite3_open_v2, 
                       _sqlite3_os_end, _sqlite3_os_init, _sqlite3_overload_function, 
                       _sqlite3_prepare, _sqlite3_prepare16, _sqlite3_prepare16_v2, 
                       _sqlite3_prepare_v2, _sqlite3_profile, _sqlite3_progress_handler, 
                       _sqlite3_randomness, _sqlite3_realloc, _sqlite3_realloc64, 
                       _sqlite3_release_memory, _sqlite3_reset, _sqlite3_reset_auto_extension, 
                       _sqlite3_result_blob, _sqlite3_result_blob64, _sqlite3_result_double, 
                       _sqlite3_result_error, _sqlite3_result_error16, 
                       _sqlite3_result_error_code, _sqlite3_result_error_nomem, 
                       _sqlite3_result_error_toobig, _sqlite3_result_int, 
                       _sqlite3_result_int64, _sqlite3_result_null, _sqlite3_result_text, 
                       _sqlite3_result_text16, _sqlite3_result_text16be, 
                       _sqlite3_result_text16le, _sqlite3_result_text64, 
                       _sqlite3_result_value, _sqlite3_result_zeroblob, 
                       _sqlite3_rollback_hook, _sqlite3_rtree_geometry_callback, 
                       _sqlite3_rtree_query_callback, _sqlite3_set_authorizer, 
                       _sqlite3_set_auxdata, _sqlite3_shutdown, _sqlite3_sleep, 
                       _sqlite3_snprintf, _sqlite3_soft_heap_limit, _sqlite3_soft_heap_limit64, 
                       _sqlite3_sourceid, _sqlite3_sql, _sqlite3_status, 
                       _sqlite3_status64, _sqlite3_step, _sqlite3_stmt_busy, 
                       _sqlite3_stmt_readonly, _sqlite3_stmt_status, _sqlite3_strglob, 
                       _sqlite3_stricmp, _sqlite3_strnicmp, _sqlite3_table_column_metadata, 
                       _sqlite3_temp_directory, _sqlite3_test_control, 
                       _sqlite3_thread_cleanup, _sqlite3_threadsafe, _sqlite3_total_changes, 
                       _sqlite3_trace, _sqlite3_transfer_bindings, _sqlite3_update_hook, 
                       _sqlite3_uri_boolean, _sqlite3_uri_int64, _sqlite3_uri_parameter, 
                       _sqlite3_user_data, _sqlite3_value_blob, _sqlite3_value_bytes, 
                       _sqlite3_value_bytes16, _sqlite3_value_double, _sqlite3_value_int, 
                       _sqlite3_value_int64, _sqlite3_value_numeric_type, 
                       _sqlite3_value_text, _sqlite3_value_text16, _sqlite3_value_text16be, 
                       _sqlite3_value_text16le, _sqlite3_value_type, _sqlite3_version, 
                       _sqlite3_vfs_find, _sqlite3_vfs_register, _sqlite3_vfs_unregister, 
                       _sqlite3_vmprintf, _sqlite3_vsnprintf, _sqlite3_vtab_config, 
                       _sqlite3_vtab_on_conflict, _sqlite3_wal_autocheckpoint, 
                       _sqlite3_wal_checkpoint, _sqlite3_wal_checkpoint_v2, 
                       _sqlite3_wal_hook ]
...

---

您没有收到重复的符号链接器错误，因为您只包含一个二进制库，

libsqlcipher.a

。如果希望在iOS应用程序中使用SQLCipher，则需要删除

libsqlite3.tbd

引用并包含

libsqlcipher.a

。

我遇到了同样的问题，如果不删除libsqlite3.0.tbd，加密将取决于iOS系统，在iOS 13及更高版本中，将使用系统算法进行加密，在iOS 12和更早的版本上，数据库不会被加密

---

您没有收到重复符号错误，因为系统sqlite是一个动态库。

非常感谢！但我做了另一个实验。。。我从www.sqlite.org下载sqlite源代码，并将sqlite3.hsqlite3.c添加到项目中。重复符号错误仍然没有发生…您确定正确链接了libsqlcipher.a吗？是的。libsqlcipher.a是唯一一个添加到链接二进制库中的库。我用hexdump检查了创建的sqlite数据库文件，它确实是加密的。我认为sqlcipher没有什么问题，我只是好奇这个问题。我还尝试了其他组合：libsqlite3.0.dylib与sqlite3源文件、wxSQLite3与sqlite3源文件、libsqlite3.0.dylib与wxSQLite3，但没有发生错误。许多相关教程也提到不要将xxx与yyy一起添加，否则可能会出现重复符号错误。但是，错误不会发生。。。