子类化UINavigationBar的方式修改导航栏的高度

 [self.navigationController setValue:[[YALNavigationBar alloc]init] forKeyPath:@"navigationBar"];


@interface YALNavigationBar : UINavigationBar
@end


static float const defaultHeight = 65.f;


#import "YALNavigationBar.h"


@implementation YALNavigationBar


- (CGSize)sizeThatFits:(CGSize)size {
    
    CGSize amendedSize = [super sizeThatFits:size];
    amendedSize.height = defaultHeight;
    
    return amendedSize;
}