1.首先在Appdelegate的啟動方法里設置

     UIImage *backButtonImage = [[UIImage imageNamed:@"fanhui"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    [[UINavigationBar appearance] setBackIndicatorImage:backButtonImage];
    [[UINavigationBar appearance] setBackIndicatorTransitionMaskImage:backButtonImage];

這樣會替換系統(tǒng)原來的返回按鈕圖片。
2.將文字設置一定的偏移量

//iOS11之后
[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(-200, 0)
                                                         forBarMetrics:UIBarMetricsDefault];
//iOS11之前
[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60)
                                                         forBarMetrics:UIBarMetricsDefault];