Here are iOS 9+ Objective-C headers as derived from runtime introspection.

For headers before iOS 9, please check out nst/iOS-Runtime-Headers.

You can search the headers with GitHub search:

https://github.com/ElfSundae/iOS-Runtime-Headers/search?q=UIView

You can compare versions based on their tags, see the tags page:

$ git difftool 10.0 10.1 .

You can use the headers this way:

NSBundle *b = [NSBundle bundleWithPath:@"/System/Library/PrivateFrameworks/FTServices.framework"];
BOOL success = [b load];

Class FTDeviceSupport = NSClassFromString(@"FTDeviceSupport");
id si = [FTDeviceSupport valueForKey:@"sharedInstance"];

NSLog(@"-- %@", [si valueForKey:@"deviceColor"]);

The headers were generated using RuntimeBrowser for iPhone.

First build and run iOS OCRuntime > Frameworks tab > Load All, then run:

wget -r -np -t 15 -R "index.html*" -nH -P iOS-Runtime-Headers http://192.168.2.123:10000/tree/