Iphone 设置Xcode 4.2.1时出错？

我在尝试设置Xcode时遇到问题。如图所示

下面是我的install.log文件中的内容：

Apr 1 01:29:04 Bashars-MacBook-Pro Installer[420]: Create temporary directory "/var/folders/_4/pnfcjvx94hbgzfgsyy387b9w0000gn/T//Install.420mLpMwf" Apr 1 01:29:04 Bashars-MacBook-Pro Installer[420]: IFPKInstallElement (29 packages) Apr 1 01:29:04 Bashars-MacBook-Pro Installer[420]: Using authorization level of root for IFPKInstallElement Apr 1 01:29:04 Bashars-MacBook-Pro Installer[420]: Failed install preflight: Error Domain=PKInstallErrorDomain Code=102 "The package “DeveloperTools.pkg” is untrusted." UserInfo=0x7fb8526d33d0 {NSLocalizedDescription=The package “DeveloperTools.pkg” is untrusted., NSURL=../Packages/DeveloperTools.pkg -- file://localhost/Users/bashar/Desktop/Programs/Xcode%204.2.1%20iOS%205/Install%20Xcode.app/Contents/Resources/Xcode.mpkg/, PKInstallPackageIdentifier=com.apple.pkg.DeveloperToolsLeo, NSUnderlyingError=0x7fb8526b61e0 "The operation couldn’t be completed. CSSMERR_TP_CERT_EXPIRED"} Apr 1 01:29:04 Bashars-MacBook-Pro Installer[420]: Install failed: The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance. Apr 1 01:29:04 Bashars-MacBook-Pro Installer[420]: IFDInstallController 50D06C30 state = 7 Apr 1 01:29:04 Bashars-MacBook-Pro Installer[420]: Displaying 'Install Failed' UI. Apr 1 01:29:04 Bashars-MacBook-Pro Installer[420]: 'Install Failed' UI displayed message:'An unknown installation error occurred.

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用于签名的证书已过期。将您的日期设置为4.2.1发布的日期，然后安装它。

这个问题可能在这里没有讨论过。

The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.'.