It would seem that they did all this last year and this should not cause any problems. But it was not there. Today it became necessary to restore the system from backup, and there the old Xcode. It seems that the problem is not great: developer accounting is in order - go to developer.apple.com/xcode and download. But there Xcode 4.3.2, and, as you know, it is put only on the Lion ...
There are various reasons why some decided not to upgrade to Lion: someone did not like it; someone decided to save money, having learned that the next version will be very soon; for someone, everything is simply already set up and too lazy to change something that already works; and someone had difficulty installing a hackintosh on a system with an AMD processor and his Lion simply would not work. This is a topic for another conversation. It is important that I do not want to upgrade the system to Lion. Especially now, when a couple of months remain before the mountain lion. All I need is an SDK for iOS 5. This SDK is in Xcode 4.2 and it worked perfectly and was completely fine.
In additional downloads, the required version was found. But after downloading, I constantly received an unknown error:

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The cause of the error was found in /var/log/install.log:
Failed install preflight: Error Domain=PKInstallErrorDomain Code=102 UserInfo=0x1112aab20 "The package “OpenGLApps.pkg” is untrusted." Underlying Error=(Error Domain=NSOSStatusErrorDomain Code=-2147409654 UserInfo=0x1126642c0 "The operation couldn't be completed. CSSMERR_TP_CERT_EXPIRED")
Obviously, the problem is with the certificate for “OpenGLApps.pkg”. CSSMERR_TP_CERT_EXPIRED googling has led to
stackoverflow . The solution is trivial to disgrace - stupidly put the date away into the past, when the certificate was still valid.
Actually, the essence of the post:
1. Xcode 4.2 for Snow Leopard
is on the Apple website (you need to have a developer account and be logged in to download)
2. To establish everything enough to change the date (on stackoverflow, they say - until March 26, 2012)