在导航栏iOS6中设置UILabel宽度

Question

我遇到与UINavigationItem title label set width?类似的问题我将后退按钮添加为子视图

 [self.navigationController.navigationBar addSubview:backButton];

和我的方法只适用于[iOS ver]＆lt; 6

-(void)setNavTitle:(NSString *)title{
    UILabel *label;
    CGRect frame = CGRectMake(0, 0, 220, 44);
    label= [[[UILabel alloc] initWithFrame:frame] autorelease];
    label.backgroundColor = [UIColor clearColor];
    label.textAlignment = NSTextAlignmentCenter;
    [label setBaselineAdjustment:UIBaselineAdjustmentAlignCenters];
    [label setMinimumFontSize:6.0];
    [label setAdjustsFontSizeToFitWidth:TRUE];
    label.textColor = [UIColor whiteColor];
    label.text = title;
    self.navigationItem.titleView=label;

}

如何强制此代码与iOS6一起使用？谢谢你的帮助！