Show/hide UIToolbar, “match finger movement”, precisely as in for example iOS7 Safari

Question

Note: check out Thuy\'s great subclass of UINavBar here:

https://stackoverflow.com/a/20720359/294884

If you\'re working on this problem, GTScrollNavigationBa

Answer 1

There is no open-source that does this, but I don't see it as that difficult to implement. It may be somewhat more difficult to have the exact 1:1 behavior as Safari, but it can still be done.

MobileSafar can be attached to in the debugger and, using breakpoints and the Objective C runtime, debugged and reverse engineered.

For example, your two assumptions that no toolbar and navigation bars are used are incorrect.

Here is the view hierarchy before scrolling:

http://pastebin.com/aRXr7b5Z

And after scrolling:

http://pastebin.com/CasBNuxq

As you can see, the bars have been moved from their normal location.

Breaking on -[BrowserToolbar setFrame:], here is the stack trace:

* thread #1: tid = 0x2332c, 0x000000010003fa70 MobileSafari`___lldb_unnamed_function1519$$MobileSafari, queue = 'com.apple.main-thread', stop reason = breakpoint 8.1
  * frame #0: 0x000000010003fa70 MobileSafari`___lldb_unnamed_function1519$$MobileSafari
    frame #1: 0x0000000100023e51 MobileSafari`___lldb_unnamed_function825$$MobileSafari + 1338
    frame #2: 0x00000001000268da MobileSafari`___lldb_unnamed_function871$$MobileSafari + 55
    frame #3: 0x000000010009856a MobileSafari`___lldb_unnamed_function3864$$MobileSafari + 388
    frame #4: 0x0000000100098996 MobileSafari`___lldb_unnamed_function3871$$MobileSafari + 154
    frame #5: 0x000000010002ba89 MobileSafari`___lldb_unnamed_function990$$MobileSafari + 209
    frame #6: 0x0000000102396a8c UIKit`-[UIScrollView(UIScrollViewInternal) _notifyDidScroll] + 55
    frame #7: 0x000000010238692b UIKit`-[UIScrollView setContentOffset:] + 628
    frame #8: 0x000000010238ab00 UIKit`-[UIScrollView _updatePanGesture] + 1989
    frame #9: 0x0000000102644002 UIKit`_UIGestureRecognizerSendActions + 188
    frame #10: 0x0000000102642f68 UIKit`-[UIGestureRecognizer _updateGestureWithEvent:buttonEvent:] + 357
    frame #11: 0x0000000102647319 UIKit`___UIGestureRecognizerUpdate_block_invoke + 53
    frame #12: 0x00000001026472a1 UIKit`_UIGestureRecognizerRemoveObjectsFromArrayAndApplyBlocks + 257
    frame #13: 0x000000010263f377 UIKit`_UIGestureRecognizerUpdate + 93
    frame #14: 0x0000000102353e55 UIKit`-[UIWindow _sendGesturesForEvent:] + 928
    frame #15: 0x0000000102354b14 UIKit`-[UIWindow sendEvent:] + 909
    frame #16: 0x000000010232c6da UIKit`-[UIApplication sendEvent:] + 211
    frame #17: 0x0000000102319f2d UIKit`_UIApplicationHandleEventQueue + 9579
    frame #18: 0x0000000100573f21 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    frame #19: 0x00000001005737f2 CoreFoundation`__CFRunLoopDoSources0 + 242
    frame #20: 0x000000010058f66f CoreFoundation`__CFRunLoopRun + 767
    frame #21: 0x000000010058ef83 CoreFoundation`CFRunLoopRunSpecific + 467
    frame #22: 0x00000001011a0f04 GraphicsServices`GSEventRunModal + 161
    frame #23: 0x000000010231c273 UIKit`UIApplicationMain + 1010
    frame #24: 0x00000001000518d2 MobileSafari`___lldb_unnamed_function1998$$MobileSafari + 1558

So it all happens after a notification of scrolling.

I put a breakpoint on MobileSafari'___lldb_unnamed_function990$$MobileSafari and to get the self variable, print po $arg1. This is where all the magic happens:

http://pastebin.com/kjAXKKTW

If you are really interested in 1:1 replication, you can put breakpoints on these methods and investigate. Good luck!