全局定义导航栏返回键

UIImage *backImage = [UIImage imageRendingMode:@"back-arrow"];
NSLog(@"%f",backImage.size.width);
[[UIBarButtonItem appearance] setBackButtonBackgroundImage:[backImage resizableImageWithCapInsets:UIEdgeInsetsMake(0, 11, 0, 0)] forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0,0)
forBarMetrics:UIBarMetricsDefault];
[[UIBarButtonItem appearance] setTitleTextAttributes:@{NSFontAttributeName: [UIFont systemFontOfSize:0.1], NSForegroundColorAttributeName: [UIColor clearColor]} forState:UIControlStateNormal];