如何修改UINavigationBar的高度

新建一个UINavigationBar的Category，如下：

@implementation UINavigationBar (CustomHeight)- (CGSize)sizeThatFits:(CGSize)size {    // Change navigation bar height. The height must be even, otherwise there will be a white line above the navigation bar.    CGSize newSize = CGSizeMake(self.frame.size.width, 74);    return newSize;}-(void)layoutSubviews {    [super layoutSubviews];        CGRect barFrame = self.frame;    barFrame.size.height = 74;    self.frame = barFrame;        // Make items on navigation bar vertically centered.    int i = 0;    for (UIView *view in self.subviews) {        if (i == 0)            continue;        float centerY = self.bounds.size.height / 2.0f;        CGPoint center = view.center;        center.y = centerY;        view.center = center;    }}@end

注意：如果只重载sizeThatFits函数，则可能出现UINavigationBar宽度不正确的现象，因为在这时获得的frame可能不正确。