change UIBarButtonItem style

I create UIBarButtonItem using

UIBarButtonItem *previous = [[UIBarButtonItem alloc] 
                             initWithTitle:@"Search"
                             style:UIBarButtonItemStyleBordered
                             target:self
                             action:@select开发者_运维百科or(SearchAction:)];

how to change its style to black

best regards

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Set the tint color of UINavigationBar to black.