修改navigationItem上的title 颜色和样式

废话不多说，直接上代码，alloc一个lable赋值给self.navigationItem.titleView就行了
UILabel *label = [[UILabel alloc] initWithFrame:CGRectZero];
label.backgroundColor = [UIColor clearColor];
label.font = [UIFont boldSystemFontOfSize:30.0];
label.textAlignment = NSTextAlignmentCenter;
label.textColor = [UIColor whiteColor];
self.navigationItem.titleView = label;
label.text = @"广州洛维建筑信息技术咨询有限公司";
[label sizeToFit];