How to set custom font family as system font in ios application [duplicate]

Answer 1

I had your same problem when updating my iOS app for iOS 7. I wanted to set a custom font for the entire application, even for controls you are not allowed to customize their font (e.g. pickers).
After a bit of research on the web and on Twitter, I solved using Method Swizzling which is a practice that consists in exchanging method implementations.

NOTE: This method might be dangerous if not used carefully! Read this discussion on SO: Dangers of Method Swizzling

However, this is what to do:

1. Create a UIFont category, like UIFont+CustomSystemFont.
2. Import in your .m file.
3. Leave .h file unmodified and add this code to the .m:

+(UIFont *)regularFontWithSize:(CGFloat)size
{
  return [UIFont fontWithName:@"Your Font Name Here" size:size];
}

+(UIFont *)boldFontWithSize:(CGFloat)size
{
  return [UIFont fontWithName:@"Your Bold Font Name Here" size:size];
}

// Method Swizzling

+(void)load
{
    SEL original = @selector(systemFontOfSize:);
    SEL modified = @selector(regularFontWithSize:);
    SEL originalBold = @selector(boldSystemFontOfSize:);
    SEL modifiedBold = @selector(boldFontWithSize:);

    Method originalMethod = class_getClassMethod(self, original);
    Method modifiedMethod = class_getClassMethod(self, modified);
    method_exchangeImplementations(originalMethod, modifiedMethod);

    Method originalBoldMethod = class_getClassMethod(self, originalBold);
    Method modifiedBoldMethod = class_getClassMethod(self, modifiedBold);
    method_exchangeImplementations(originalBoldMethod, modifiedBoldMethod);
}