Allow latest app version to be dependent on current system version

Source/EmUpAppController.m

 /* Copyright (c) 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 121 matching lines @@
 NSURLRequest *request = [NSURLRequest requestWithURL:plistURL];
 GDataHTTPFetcher *fetcher = [GDataHTTPFetcher httpFetcherWithRequest:request];
 
 [fetcher beginFetchWithDelegate:self
 didFinishSelector:@selector(plistFetcher:finishedWithData:)
 didFailSelector:@selector(plistFetcher:failedWithError:)];
 
 [fetcher setUserData:[NSNumber numberWithBool:shouldForceUpdate]];
 }
 
+- (NSString *)appVersionForCurrentSystemVersionWithMap:(NSDictionary *)versionMa p {
+// using a dictionary mapping system version ranges to app versions, like
+// -10.4.11 : 1.1.2
+// 10.5-10.5.8 : 1.1.3
+// 10.6- : 1.1.4
+// find the latest app version for the current system
+//
+// note: the system ranges should have no holes or overlapping system
+// versions, and should not be order-dependent
+
+SInt32 systemMajor = 0, systemMinor = 0, systemRelease = 0;
+(void) Gestalt(gestaltSystemVersionMajor, &systemMajor);
+(void) Gestalt(gestaltSystemVersionMinor, &systemMinor);
+(void) Gestalt(gestaltSystemVersionBugFix, &systemRelease);
+
+NSString *systemVersion = [NSString stringWithFormat:@"%d.%d.%d",
+(int)systemMajor, (int)systemMinor, (int)systemRele ase];
+NSString *versionRange;
+GDATA_FOREACH_KEY(versionRange, versionMap) {
+
+NSString *lowSystemVersion = nil;
+NSString *dash = nil;
+NSString *highSystemVersion = nil;
+NSComparisonResult comp1, comp2;
+
+// parse "low", "low-", "low-high", or "-high"
+NSScanner *scanner = [NSScanner scannerWithString:versionRange];
+[scanner scanUpToString:@"-" intoString:&lowSystemVersion];
+[scanner scanString:@"-" intoString:&dash];
+[scanner scanUpToString:@"\r" intoString:&highSystemVersion];
+
+BOOL doesMatchLow = YES;
+BOOL doesMatchHigh = YES;

[TVL, 2010/04/15 11:23:03]

"match" isn't really right here, but I'm not coming up with anything better that isn't a paragraph. 

+
+if (lowSystemVersion) {
+comp1 = [GDataUtilities compareVersion:lowSystemVersion
+toVersion:systemVersion];
+doesMatchLow = (comp1 == NSOrderedSame
+|| (dash != nil && comp1 == NSOrderedAscending));
+}
+
+if (highSystemVersion) {
+comp2 = [GDataUtilities compareVersion:highSystemVersion
+toVersion:systemVersion];
+doesMatchHigh = (comp2 == NSOrderedSame
+|| (dash != nil && comp2 == NSOrderedDescending));
+}
+
+if (doesMatchLow && doesMatchHigh) {
+NSString *result = [versionMap objectForKey:versionRange];
+return result;
+}
+}
+
+return nil;
+}
+
 - (void)plistFetcher:(GDataHTTPFetcher *)fetcher finishedWithData:(NSData *)data {
 // convert the returns data to a plist dictionary
 NSString *errorStr = nil;
 NSDictionary *plist;
 
 plist = [NSPropertyListSerialization propertyListFromData:data
 mutabilityOption:NSPropertyListImmuta ble
 format:NULL
 errorDescription:&errorStr];
 
 if ([plist isKindOfClass:[NSDictionary class]]) {
- // compare the plist's short version string with the one in this bundle
- NSString *latestVersion = [plist objectForKey:@"CFBundleShortVersionString"]  ;
+
+ // get the map of system versions to app versions, and step through the
+ // system version ranges to find the latest app version for this system
+ NSString *latestVersion;
+ NSDictionary *versionMap = [plist objectForKey:@"SystemToVersionMap"];
+ if (versionMap) {
+ // new, with the map
+ latestVersion = [self appVersionForCurrentSystemVersionWithMap:versionMap]  ;
+ } else {
+ // old, without the map
+ latestVersion = [plist objectForKey:@"CFBundleShortVersionString"];
+ }
+
+ // compare the short version string in this bundle to the one from the
+ // map
 NSString *thisVersion = [[NSBundle mainBundle] objectForInfoDictionaryKey:@" CFBundleShortVersionString"];
 
 NSComparisonResult result = [GDataUtilities compareVersion:thisVersion
 toVersion:latestVersion];
 
 BOOL shouldForceUpdate = [[fetcher userData] boolValue];
 
 if (result != NSOrderedAscending && !shouldForceUpdate) {
 // we're current; do nothing
 } else {
@@ skipping 31 matching lines @@
 [[NSWorkspace sharedWorkspace] openURL:[NSURL URLWithString:urlStr]];
 }
 }
 
 - (void)plistFetcher:(GDataHTTPFetcher *)fetcher failedWithError:(NSError *)erro r {
 // nothing to do but report this on the console
 NSLog(@"unable to fetch plist at %@, %@", [[fetcher request] URL], error);
 }
 
 @end