UIFont *barButtonTitleFont = [UIFont fontWithName:@"mplus-2p-light" size:13];
UIColor *barButtonTitleColor = [UIColor whiteColor];
[[UIBarButtonItem appearance] setTitleTextAttributes:@{UITextAttributeFont:barButtonTitleFont, UITextAttributeTextColor:barButtonTitleColor} forState:UIControlStateNormal];
を記述。これで、BackButtonのフォントが変わる次に、NavigationControllerの『ViewDidLoad』に、
UILabel* label = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 200, 44)];
label.backgroundColor = [UIColor clearColor];
label.font = [UIFont fontWithName:@"mplus-2p-light" size:22.0f];
label.textColor = [UIColor flatWhiteColor];
label.text = @"タイトル";
label.textAlignment = NSTextAlignmentCenter;
self.navigationItem.titleView = label;
を記述。これで、タイトルのフォントが変わる。それはそうと、m+フォントってとても美しいよね

