iOS开发Xcode8的log输出“__nwlog_err_si

『导言』

亲呐，你有木有升级xcode8？有木有遇到这样的输出，老长了，怎么办？

• 分析：

升级xcode8后，屏蔽后台的多余的输出log输出：

objc[2126]: Class PLBuildVersion is implemented in both /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/System/Library/PrivateFrameworks/AssetsLibraryServices.framework/AssetsLibraryServices (0x12ce244c) and /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/System/Library/PrivateFrameworks/PhotoLibraryServices.framework/PhotoLibraryServices (0x12b23b78). One of the two will be used. Which one is undefined.
2017-04-05 11:38:20.033821 DeliciousFoodDemo[2126:87760] [] nw_host_stats_add_src recv too small, received 24, expected 28
2017-04-05 11:38:20.039139 DeliciousFoodDemo[2126:87760] [] ____nwlog_simulate_crash_inner_block_invoke dlopen CrashReporterSupport failed
2017-04-05 11:38:20.039711 DeliciousFoodDemo[2126:87760] [] __nwlog_err_simulate_crash simulate crash failed "nw_socket_set_common_sockopts setsockopt SO_NOAPNFALLBK failed: [42] Protocol not available"
2017-04-05 11:38:20.041064 DeliciousFoodDemo[2126:87760] [] nw_socket_set_common_sockopts setsockopt SO_NOAPNFALLBK failed: [42] Protocol not available, dumping backtrace:
        [i386] libnetcore-856.30.16
    0   libsystem_network.dylib             0x032f414d __nw_create_backtrace_string + 123
    1   libnetwork.dylib                    0x043fa7a6 nw_socket_add_input_handler + 3588
    2   libnetwork.dylib                    0x043d56fe nw_endpoint_flow_attach_protocols + 4199
    3   libnetwork.dylib                    0x043d457a nw_endpoint_flow_setup_socket + 581
    4   libnetwork.dylib                    0x043d31ed -[NWConcrete_nw_endpoint_flow startWithHandler:] + 2545
    5   libnetwork.dylib                    0x043f0cf0 nw_endpoint_handler_path_change + 2835
    6   libnetwork.dylib                    0x043f00f6 nw_endpoint_handler_start + 589
    7   libnetwork.dylib                    0x044098c0 nw_endpoint_resolver_start_next_child + 2634
    8   libdispatch.dylib                   0x03092396 _dispatch_call_block_and_release + 15
    9   libdispatch.dylib                   0x030bdcc3 _dispatch_client_callout + 14
    10  libdispatch.dylib                   0x0309a3ae _dispatch_queue_serial_drain + 1619
    11  libdispatch.dylib                   0x0309abc2 _dispatch_queue_invoke + 1109
    12  libdispatch.dylib                   0x0309d5e4 _dispatch_root_queue_drain + 470
    13  libdispatch.dylib                   0x0309d3a6 _dispatch_worker_thread3 + 143
    14  libsystem_pthread.dylib             0x0350e25c _pthread_wqthread + 1050
    15  libsystem_pthread.dylib             0x0350bf56 start_wqthread + 34

解决方法

• 首先，找到Environment Variable
  • 找到在Xcode的菜单栏，依次进入：
    【product】-【scheme】-【Edit Scheme】-【Run】-【Argument】-【Environment Variable】</br>
• 或 快捷键操作：
  快捷键【 shift】＋【command】 ＋ 【< 】
  图.添加设置
• 然后,点击+添加进行设置

key	value
OS_ACTIVITY_MODE	disable

图.设置
动态教程.gif

• 补充：

• 遗留问题：还会出现,属于正常现象

Class PLBuildVersion is implemented2017-04-05 11:05:47.616 DeliciousFoodDemo[2090:68216] http://api.2meiwei.com/v1/index/index/
objc[2090]: Class PLBuildVersion is implemented in both /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/System/Library/PrivateFrameworks/AssetsLibraryServices.framework/AssetsLibraryServices (0x18c0b44c) and /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/System/Library/PrivateFrameworks/PhotoLibraryServices.framework/PhotoLibraryServices (0x18a4cb78). One of the two will be used. Which one is undefined.
2017-04-05 11:05:47.778 DeliciousFoodDemo[2090:68216] 0

图.xcode8遗留问题.png

• 问题分析：
  意思是PhotoLibraryServices.framework和AssetsLibraryServices.framework产生了冲突，系统不知道用哪个
  Class PLBuildVersion在框架AssetsLibraryServices和框架PhotoLibraryServices里都有定义。在Objective-C里Class名是唯一。两个同名的Class，Xcode会选择其中一个Class来执行。PLBuildVersion在这两个框架里都是一样的，不影响实际运行。

• 在xcode8中，屏蔽了一些奇怪的输出之后，又发现了一个。具体啥原因还不是太清楚。但是可以解决这个问题，让其停止打印这个信息。

  在info.plist中，添加两个键值对：

|序号|对象|key|value|
|-------|--------|-------|
|1|针对photo|Privacy - Photo Library Usage Description| $(PRODUCT_NAME) photo use //（解释对相册的使用）|
|2|针对camera|Privacy - Camera Usage Description|$(PRODUCT_NAME) camera use //(解释对相机的使用)|

这个方法仅仅解决了photo方面的，好像别的功能（加载WebView）也会有类似的报错。
主要是因为iOS10在用户的隐私方面的改动。
并不影响程序工作，但是还没有找到完全避免的方法！
更新到Xcode新版本之后，这个打印已经没有了。比如：使用的是Xcode 8.2.1。没有这个打印问题！

图.plist设置.png