A program that adds the UUID of the current installation of Xcode (in /Applications/Xcode.app) to every Xcode plug-in's Info.plist. Does nothing if the plug-in already contains the current UUID.

UpdateXcodePluginUUIDs.m

//
//  main.m
//  UpdateXcodePluginUUIDs
//
//  Created by Tanner on 12/21/15.
//  Copyright © 2015 Tanner Bennett. All rights reserved.
//

#import <Foundation/Foundation.h>

NSString * const kMessage = @"\nUsage: updateudids [udid]\n";
NSString * const kPluginPath = @"/Library/Application Support/Developer/Shared/Xcode/Plug-ins/";

NSArray * RXArgsFromCharPtr(const char **vargs, int c);
NSString * PUGetLatestUUID();

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        if (argc != 1) {
            printf("%s", kMessage.UTF8String);
            return 0;
        }
        
        // Get UUID and plugin path
        NSString *uuid = PUGetLatestUUID();  uuid = [uuid substringToIndex:uuid.length-1];
        NSString *path = [NSHomeDirectory() stringByAppendingString:kPluginPath];
        
        // Get all plugin names
        NSArray *plugins = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:path error:nil];
        plugins = [plugins filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"self ENDSWITH '.xcplugin'"]];
        
        // Change "Foo.xcplugin" to "~/Library/.../Foo.xcplugin/Contents/Info.plist"
        plugins = ({
            NSMutableArray *fullPathsToInfoPLIST = [NSMutableArray new];
            for (NSString *plugin in plugins)
                [fullPathsToInfoPLIST addObject:[NSString stringWithFormat:@"%@%@/Contents/Info.plist", path, plugin]];
            fullPathsToInfoPLIST;
        });
        
        // Open PLIST, add UUID, write it to the file
        for (NSString *info in plugins) {
            NSMutableDictionary *plist = [NSDictionary dictionaryWithContentsOfFile:info].mutableCopy;
            if (!plist) continue;
            NSMutableSet *uuids = [NSSet setWithArray:plist[@"DVTPlugInCompatibilityUUIDs"]].mutableCopy;
            [uuids addObject:uuid];
            plist[@"DVTPlugInCompatibilityUUIDs"] = uuids.allObjects;
            [plist writeToFile:info atomically:YES];
        }
    }
    
    return 0;
}

NSString * PUGetLatestUUID() {
    NSTask *task = [NSTask new];
    task.launchPath = @"/bin/sh";
    task.arguments = @[@"-c", @"defaults read /Applications/Xcode.app/Contents/Info DVTPlugInCompatibilityUUID"];
    
    NSPipe *pipe = [NSPipe pipe];
    task.standardOutput = pipe;
    [task launch];
    
    return [[NSString alloc] initWithData:[pipe.fileHandleForReading readDataToEndOfFile] encoding:NSUTF8StringEncoding];
}