Iphone 无法读取使用Xcode 4.2进行设备调试的符号

在Xcode 4.2上调试运行iOS 5的手机时，我收到以下警告

你知道我是如何摆脱这个问题的吗？因为它会使设备上的调试变得非常缓慢。在模拟器上没问题

谢谢

GNU gdb 6.3.50-20050815 (Apple version gdb-1708) (Fri Sep 16 06:56:50 UTC 2011)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "--host=i386-apple-darwin --target=arm-apple-darwin".tty     /dev/ttys000
sharedlibrary apply-load-rules all
target remote-mobile /tmp/.XcodeGDBRemote-515-89
Switching to remote-macosx protocol
mem 0x1000 0x3fffffff cache
mem 0x40000000 0xffffffff none
mem 0x00000000 0x0fff none
[Switching to process 7171 thread 0x1c03]
[Switching to process 7171 thread 0x1c03]
Re-enabling shared library breakpoint 10
Re-enabling shared library breakpoint 11
warning: Unable to read symbols for /Users/donie/Library/Developer/Xcode/iOS     DeviceSupport/5.0.1     (9A405)/Symbols/System/Library/AccessibilityBundles/AccessibilitySettingsLoader.bundle/Accessi    bilitySettingsLoader (file not found).
warning: No copy of AccessibilitySettingsLoader.bundle/AccessibilitySettingsLoader found locally, reading from memory on remote device.  This may slow down the debug session.
warning: Unable to read symbols for /Users/donie/Library/Developer/Xcode/iOS DeviceSupport/5.0.1 (9A405)/Symbols/System/Library/AccessibilityBundles/UIKit.axbundle/UIKit (file not found).
warning: No copy of UIKit.axbundle/UIKit found locally, reading from memory on remote device.  This may slow down the debug session.
warning: Unable to read symbols for /Users/donie/Library/Developer/Xcode/iOS DeviceSupport/5.0.1 (9A405)/Symbols/System/Library/AccessibilityBundles/TwitterFramework.axbundle/TwitterFramework (file not found).
warning: No copy of TwitterFramework.axbundle/TwitterFramework found locally, reading from memory on remote device.  This may slow down the debug session.
warning: Unable to read symbols for /Users/donie/Library/Developer/Xcode/iOS DeviceSupport/5.0.1 (9A405)/Symbols/System/Library/AccessibilityBundles/MessageUIFramework.axbundle/MessageUIFramework (file not found).
warning: No copy of MessageUIFramework.axbundle/MessageUIFramework found locally, reading from memory on remote device.  This may slow down the debug session.
warning: Unable to read symbols for /Users/donie/Library/Developer/Xcode/iOS DeviceSupport/5.0.1 (9A405)/Symbols/System/Library/AccessibilityBundles/AddressBookUIFramework.axbundle/AddressBookUIFramework (file not found).
warning: No copy of AddressBookUIFramework.axbundle/AddressBookUIFramework found locally, reading from memory on remote device.  This may slow down the debug session.
warning: Unable to read symbols for /Users/donie/Library/Developer/Xcode/iOS DeviceSupport/5.0.1 (9A405)/Symbols/System/Library/AccessibilityBundles/TelephonyUIFramework.axbundle/TelephonyUIFramework (file not found).
warning: No copy of TelephonyUIFramework.axbundle/TelephonyUIFramework found locally, reading from memory on remote device.  This may slow down the debug session.
warning: Unable to read symbols for /Users/donie/Library/Developer/Xcode/iOS DeviceSupport/5.0.1 (9A405)/Symbols/System/Library/AccessibilityBundles/QuickLook.axbundle/QuickLook (file not found).
warning: No copy of QuickLook.axbundle/QuickLook found locally, reading from memory on remote device.  This may slow down the debug session.
warning: Unable to read symbols for /Users/donie/Library/Developer/Xcode/iOS DeviceSupport/5.0.1     (9A405)/Symbols/System/Library/AccessibilityBundles/MapKitFramework.axbundle/MapKitFramework     (file not found).
warning: No copy of MapKitFramework.axbundle/MapKitFramework found locally, reading from             memory on remote device.  This may slow down the debug session.

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我过去有过这样的经验，我相信唯一有效的方法就是从命令行完全卸载Xcode并重新安装

sudo /Developer/Library/uninstall-devtools --mode=all

然后重新下载并安装