自定制NavigationItem返回键

self.returnBtn= [[UIButtonalloc]initWithFrame:CGRectMake(0,0,200,25)];

[self.returnBtnsetImage:[UIImageimageNamed:@"nav_bar_back_white_icon@2x"]forState:UIControlStateNormal];

self.returnBtn.contentHorizontalAlignment=UIControlContentHorizontalAlignmentLeft;

[self.returnBtnsetTitle:@"购物车"forState:UIControlStateNormal];

[self.returnBtnsetContentEdgeInsets:UIEdgeInsetsMake(0, -12,0,0)];

[self.returnBtnsetImageEdgeInsets:UIEdgeInsetsMake(-5,0, -5,0)];

[self.returnBtnsizeToFit];

self.returnBtn.frame=CGRectMake(0,0,self.returnBtn.bounds.size.width,25);

[self.returnBtnaddTarget:selfaction:@selector(doBack:)forControlEvents:UIControlEventTouchDown];

UIBarButtonItem*btn = [[UIBarButtonItemalloc]initWithCustomView:self.returnBtn];

self.navigationItem.leftBarButtonItem= btn;