使用 Xcode 8 运行工程的时候，在打印台会发现如下这些奇怪的日志输出：

2016-09-19 10:43:44.001757 Demo[7100:171568] subsystem: com.apple.UIKit, category: HIDEventFiltered, enable_level: 0, persist_level: 0, default_ttl: 0, info_ttl: 0, debug_ttl: 0, generate_symptoms: 0, enable_oversize: 1, privacy_setting: 2, enable_private_data: 0
2016-09-19 10:43:44.024521 Demo[7100:171568] subsystem: com.apple.UIKit, category: HIDEventIncoming, enable_level: 0, persist_level: 0, default_ttl: 0, info_ttl: 0, debug_ttl: 0, generate_symptoms: 0, enable_oversize: 1, privacy_setting: 2, enable_private_data: 0
2016-09-19 10:43:44.051333 Demo[7100:171568] subsystem: com.apple.BaseBoard, category: MachPort, enable_level: 1, persist_level: 0, default_ttl: 0, info_ttl: 0, debug_ttl: 0, generate_symptoms: 0, enable_oversize: 0, privacy_setting: 0, enable_private_data: 0
2016-09-19 10:43:44.084921 Demo[7100:171568] subsystem: com.apple.UIKit, category: StatusBar, enable_level: 0, persist_level: 0, default_ttl: 0, info_ttl: 0, debug_ttl: 0, generate_symptoms: 0, enable_oversize: 1, privacy_setting: 2, enable_private_data: 0
2016-09-19 10:43:44.132757 Demo[7100:171568] subsystem: com.apple.BackBoardServices.fence, category: App, enable_level: 1, persist_level: 0, default_ttl: 0, info_ttl: 0, debug_ttl: 0, generate_symptoms: 0, enable_oversize: 0, privacy_setting: 0, enable_private_data: 0
2016-09-19 10:43:47.127087 Demo[7100:171568] subsystem: com.apple.UIKit, category: Touch, enable_level: 0, persist_level: 0, default_ttl: 1, info_ttl: 0, debug_ttl: 0, generate_symptoms: 0, enable_oversize: 1, privacy_setting: 2, enable_private_data: 0
2016-09-19 10:43:47.128826 Demo[7100:171568] subsystem: com.apple.UIKit, category: Gesture, enable_level: 0, persist_level: 0, default_ttl: 1, info_ttl: 0, debug_ttl: 0, generate_symptoms: 0, enable_oversize: 1, privacy_setting: 2, enable_private_data: 0





解决方法：
Xcode8里边 Edit Scheme... -> Run -> Arguments, 在Environment Variables里边添加 OS_ACTIVITY_MODE ＝ disable










最后点击 Close 完成！