Custom UINavigationBar height working in iOS 7 and 8. To use, find your navigation bar reference and just setHeight:200 etc.

UINavigationBar+CustomHeight.h

//
//  UINavigationBar+CustomHeight.h
//
//  Copyright (c) 2014 Maciej Swic
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.
//

#import <UIKit/UIKit.h>

@interface UINavigationBar (CustomHeight)

- (void)setHeight:(CGFloat)height;

@end

UINavigationBar+CustomHeight.m

//
//  UINavigationBar+CustomHeight.m
//
//  Copyright (c) 2014 Maciej Swic
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.
//

#import "UINavigationBar+CustomHeight.h"
#import "objc/runtime.h"

static char const *const heightKey = "Height";

@implementation UINavigationBar (CustomHeight)

- (void)setHeight:(CGFloat)height
{
    objc_setAssociatedObject(self, heightKey, @(height), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (NSNumber *)height
{
    return objc_getAssociatedObject(self, heightKey);
}

- (CGSize)sizeThatFits:(CGSize)size
{
    CGSize newSize;
    
    if (self.height) {
        newSize = CGSizeMake(self.superview.bounds.size.width, [self.height floatValue]);
    } else {
        newSize = [super sizeThatFits:size];
    }

    return newSize;
}

@end