Since Xcode 6 the device manager pane has been split into its own window. (Window > Devices, or Command-Shift-2.)
Once there, select your device, then show its log by clicking the disclosure triangle at the bottom of the window to the right of the sidebar.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…