IOS7适配之：傳回按鈕偏移問題

IOS7下用系統的UIBarButtonItem時傳回按鈕左邊距比IOS6小，見下圖：

圖1：上面是IOS6，下面是IOS7

需求：

IOS6和IOS7的傳回按鈕要統一成IOS7樣式的，即偏移量要像下面那個圖那麼寬，那IOS6怎麼辦呢？

解決方案： 

#define IOS7                 ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7)

+ (UIBarButtonItem *)backItem
{
	UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setImage:[UIImage imageNamed:STR_button_backItem]
                      forState:UIControlStateNormal];
    button.backgroundColor = [UIColor clearColor];
    CGFloat offset = 8;
    if (IOS7) {
        offset = 0;
    }
    button.frame = CGRectMake(offset, 0, kBackButtonWidth, kBackButtonHeight);
    UIView *aView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, kBackButtonWidth+offset, kBackButtonHeight)];
    button.tag = 147;
    [aView addSubview:button];
    aView.userInteractionEnabled = YES;
    UIBarButtonItem *backItem = [[UIBarButtonItem alloc] initWithCustomView:aView];
    
    
	return  backItem;
}

- (void)setTarget:(id)target action:(SEL)action
{
    UIButton *buttom = (UIButton *)[(self.customView) viewWithTag:147];
	[buttom addTarget:target action:action forControlEvents:UIControlEventTouchUpInside];
}

    //設定導航欄傳回按鈕
    UIBarButtonItem *backButton = [UIBarButtonItem backItem];
    [backButton setTarget:self action:@selector(backButtonItemClick)];
    self.navigationItem.leftBarButtonItem = backButton;
           

希望對大家有幫助~！~！