I solved this problem, just overrides the UINavigationBar & in LayoutSubViews set the height of navigationBar.
@implementation UINavigationBar (customNAvigBar)
- (void)layoutSubviews
{
[self setFrame:CGRectMake(0, 0, 320, 55)];
}
@end
that means whenever i draws the navigationBar it calls automatically & sets the height.
solved application life cycle issue