register&unregister download font error

There is a download custom font.ttf.

I register like this.

CFURLRef url = (__bridge CFURLRef)[NSURL fileURLWithPath:fontPath];

CFErrorRef error = nil;

BOOL _y = CTFontManagerRegisterFontsForURL(url,kCTFontManagerScopeProcess,&error);

if (!_y && error) {

//_y is YES and error is nil.

}

Now I do:

[UIFontfontWithName:@"Custom font name"size:14]

Then I unregister it:

CFURLRef url = (__bridgeCFURLRef)[NSURLfileURLWithPath:p];

CFErrorRef error = nil;

BOOL _y = CTFontManagerUnregisterFontsForURL(url, kCTFontManagerScopeProcess, &error);

if (!_y && error) {

//_y is YES and error is nil.

}

Now I do:

//It's always return UIFont instance

[UIFontfontWithName:@"Custom font name"size:14]

//but when I change size how much I don't use before, It's return nil

[UIFontfontWithName:@"Custom font name"size:15]

Is there cache for UIFont at OS level?

If I want update font.ttf at runtime, how to go?

Here is the effect I want:

//Before I register font, return nil

NSLog(@"%d",[UIFontfontWithName:@"Custom font name"size:14]==nil)

print:1

//When I register font, return font instance.

NSLog(@"%d",[UIFontfontWithName:@"Custom font name"size:14]==nil)

NSLog(@"%p",[UIFontfontWithName:@"Custom font name"size:14])

print:0

print:0x...

//so I can update .ttf at runtime.

//I unregister old one and register new .ttf

//I wan't get new UIFont instance without change size

//!!! Now got instance is old.

NSLog(@"%p",[UIFontfontWithName:@"Custom font name"size:14])

print:same as before!!!

//So I don't use new change from new .ttf.

Is there everybody can help me?