Base sdk 4.3给出了错误,但5.0没有给出任何错误

时间:2012-01-19 09:17:36

标签: objective-c ios4 ios5 uinavigationbar

我将当前的基本sdk设置为iOS 4.2。 我有这个方法:

    - (void) setNavigationBarBackground
    {
    if ([[[UIDevice currentDevice] systemVersion] floatValue] > 4.9) {
        //iOS 5.0
        if ([self respondsToSelector:@selector(setBackgroundImage:forBarMetrics:)])
        {
            [self setBackgroundImage:[UIImage imageNamed:kImageNavBar] forBarMetrics:UIBarMetricsDefault];
        }
    }
    else
    {
        //iOS 4.whatever and below
        UIImageView *imageView = (UIImageView *)[self viewWithTag:kNavigationBarBackgroundImageTag];
        if (imageView == nil)
        {
            imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:kImageNavBar]];
            [imageView setTag:kNavigationBarBackgroundImageTag];
            [self insertSubview:imageView atIndex:0];
            [imageView release];
        }
    }
}

当我构建项目时,遇到编译时错误:

'UIBarMetrics' Default undeclared (first use in this function)

当我将基本sdk设置为5.0时,它会编译而没有任何错误。

有谁知道如何使用base sdk 4.2编译它?

2 个答案:

答案 0 :(得分:4)

特别是你的情况,请使用:

#if defined(__IPHONE_5_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_5_0
if ([self.navigationController.navigationBar respondsToSelector:@selector( setBackgroundImage:forBarMetrics:)]){
[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"TitleBar"] forBarMetrics:UIBarMetricsDefault];
}
#endif

通常,在各种SDK版本中有条件地编译的好方法是:

将它放在顶部(连同导入):

#define SYSTEM_VERSION_EQUAL_TO(v)                  ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedSame)
#define SYSTEM_VERSION_GREATER_THAN(v)              ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedDescending)
#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(v)  ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedAscending)
#define SYSTEM_VERSION_LESS_THAN(v)                 ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)
#define SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(v)     ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedDescending)

然后如果有一些特定于操作系统的功能,请使用它们(我使用AlertView作为示例。在iOS5之前,UIAlertView不支持其中的自定义textView,因此我有自己的自定义AlertView。在iOS5中, hack不起作用,我必须使用UIAlertView,因为它支持自定义textViews):

if (SYSTEM_VERSION_LESS_THAN(@"5.0")) {

TextAlertView *alert = [[TextAlertView alloc] initWithTitle:@"xxxYYzz" 
                                                    message:@"" 
                                                   delegate:self cancelButtonTitle:@"Add"
                                          otherButtonTitles:@"Cancel", nil];
alert.textField.keyboardType = UIKeyboardTypeDefault;
alert.tag = 1;
self.recipeNameTextField = alert.textField;
[alert show];
[alert release];
}
else {
     UIAlertView* alert = [[UIAlertView alloc] initWithTitle:@"xxYYzz"
                                           message:@"" 
                                           delegate:self cancelButtonTitle:@"Add"
                                  otherButtonTitles:@"Cancel", nil];
     alert.alertViewStyle = UIAlertViewStylePlainTextInput;
     self.recipeNameTextField = [alert textFieldAtIndex:0];

     [alert show];
     [alert release];
 }

希望有所帮助

答案 1 :(得分:0)

将“基本SDK”设置为“最新iOS”。

将“iOS部署目标”设置为您要支持的最低版本,在本例中为“iOS 4.2”。