如何检测旧的安装和报价删除？

Question

如何检测用户是否已安装软件，如果有，如何提供删除旧版本的可能性？

我写了一些行来检查。现在是否正确？如果这是正确的，那么我该如何让用户选择是否要继续安装或卸载旧版本？

#define UNINSTKEY "Software\Microsoft\Windows\CurrentVersion\Uninstall\setupname_is1" 

var 
    uninstallPath: string; 

function InitializeSetup: Boolean; 
begin 
    if (RegQueryStringValue(HKLM,'{#UNINSTKEY}','UninstallString',uninstallPath)) and 
    (uninstallPath <> '') and (fileexists(uninstallPath)) then 
    begin 
    Result := 
     (MsgBox(CustomMessage('NotVerifiedVersionFound'), mbConfirmation, 
       MB_YESNO or MB_DEFBUTTON2) = IDYES); 
    end; 
    { ... } 
end; 

Answer 1

你可以使用克雷格·麦昆的解决方案在这里原贴：InnoSetup: How to automatically uninstall previous installed version?

function GetUninstallString: string; 
var 
    sUnInstPath: string; 
    sUnInstallString: String; 
begin 
    Result := ''; 
    sUnInstPath := ExpandConstant('Software\Microsoft\Windows\CurrentVersion\Uninstall\{{A227028A-40D7-4695-8BA9-41DF6A3895C7}_is1'); { Your App GUID/ID } 
    sUnInstallString := ''; 
    if not RegQueryStringValue(HKLM, sUnInstPath, 'UninstallString', sUnInstallString) then 
    RegQueryStringValue(HKCU, sUnInstPath, 'UninstallString', sUnInstallString); 
    Result := sUnInstallString; 
end; 

function IsUpgrade: Boolean; 
begin 
    Result := (GetUninstallString() <> ''); 
end; 

function InitializeSetup: Boolean; 
var 
    V: Integer; 
    iResultCode: Integer; 
    sUnInstallString: string; 
begin 
    Result := True; { in case when no previous version is found } 
    if RegValueExists(HKEY_LOCAL_MACHINE,'Software\Microsoft\Windows\CurrentVersion\Uninstall\{A227028A-40D7-4695-8BA9-41DF6A3895C7}_is1', 'UninstallString') then { Your App GUID/ID } 
    begin 
    V := MsgBox(ExpandConstant('Hey! An old version of app was detected. Do you want to uninstall it?'), mbInformation, MB_YESNO); { Custom Message if App installed } 
    if V = IDYES then 
    begin 
     sUnInstallString := GetUninstallString(); 
     sUnInstallString := RemoveQuotes(sUnInstallString); 
     Exec(ExpandConstant(sUnInstallString), '', '', SW_SHOW, ewWaitUntilTerminated, iResultCode); 
     Result := True; { if you want to proceed after uninstall } 
     { Exit; //if you want to quit after uninstall } 
    end 
    else 
     Result := False; { when older version present and not uninstalled } 
    end; 
end;