iOS UIAppearance使用详解

iOS5及其以后提供了一个比较强大的工具UIAppearance，我们通过UIAppearance设置一些UI的全局效果，这样就可以很方便的实现UI的自定义效果又能最简单的实现统一界面风格，它提供如下两个方法。
+ (id)appearance
这个方法是统一全部改，比如你设置UINavBar的tintColor，你可以这样写：[[UINavigationBar appearance] setTintColor:myColor];

• (id)appearanceWhenContainedIn:(Class <>)ContainerClass,…
  这个方法可设置某个类的改变：例如：设置UIBarButtonItem 在UINavigationBar、UIPopoverController、UITabbar中的效果。就可以这样写
  [[UIBarButtonItem appearanceWhenContainedIn:[UINavigationBar class], [UIPopoverController class],[UITabbar class] nil] setTintColor:myPopoverNavBarColor];

请注意＊使用appearance设置UI效果最好采用全局的设置，在所有界面初始化前开始设置，否则可能失效。

具体UI外观修改如下：

1.修改导航栏背景
代码如下：

UINavigationBar * appearance = [UINavigationBar appearance];UIImage *navBackgroundImg =[UIImage imageNamed:@"navBg.png”];[appearance setBackgroundImage:navBackgroundImg forBarMetrics:UIBarMetricsDefault];

2.标签栏（UITabbar）
代码如下：

UITabBar *appearance = [UITabBar appearance];//设置背景图片[appearance setBackgroundImage:[UIImage imageNamed:@"tabbar_bg.png"]];//门置选择item的背景图片UIImage * selectionIndicatorImage =[[UIImage imageNamed:@"tabbar_slider"]resizableImageWithCapInsets:UIEdgeInsetsMake(4, 0, 0, 0)] ;[appearance setSelectionIndicatorImage:selectionIndicatorImage];

3.分段控件（UISegmentControl）
代码如下：

UISegmentedControl *appearance = [UISegmentedControl appearance];//Segmenteg正常背景[appearance setBackgroundImage:[UIImage imageNamed:@"Segmente.png"]                      forState:UIControlStateNormal                    barMetrics:UIBarMetricsDefault];//Segmente选中背景[appearance setBackgroundImage:[UIImage imageNamed:@"Segmente_a.png"]                      forState:UIControlStateSelected                    barMetrics:UIBarMetricsDefault];//Segmente左右都未选中时的分割线//BarMetrics表示navigation bar的状态，UIBarMetricsDefault 表示portrait状态（44pixel height），UIBarMetricsLandscapePhone 表示landscape状态（32pixel height）[appearance setDividerImage:[UIImage imageNamed:@"Segmente_line.png"]        forLeftSegmentState:UIControlStateNormal          rightSegmentState:UIControlStateNormal                 barMetrics:UIBarMetricsDefault];[appearance setDividerImage:[UIImage imageNamed:@"Segmente_line.png"]        forLeftSegmentState:UIControlStateSelected          rightSegmentState:UIControlStateNormal                 barMetrics:UIBarMetricsDefault];[appearance setDividerImage:[UIImage imageNamed:@"Segmente_line.png"]        forLeftSegmentState:UIControlStateNormal          rightSegmentState:UIControlStateSelected                 barMetrics:UIBarMetricsDefault];//字体NSDictionary *textAttributes1 = @{UITextAttributeFont: [UIFont systemFontOfSize:18],                                 UITextAttributeTextColor: [UIColor blueColor],                                 UITextAttributeTextShadowColor: [UIColor whiteColor],                                 UITextAttributeTextShadowOffset: [NSValue valueWithCGSize:CGSizeMake(1, 1)]};[appearance setTitleTextAttributes:textAttributes1 forState:1];NSDictionary *textAttributes2 = @{UITextAttributeFont: [UIFont systemFontOfSize:18],                                 UITextAttributeTextColor: [UIColor whiteColor],                                 UITextAttributeTextShadowColor: [UIColor blackColor],                                 UITextAttributeTextShadowOffset: [NSValue valueWithCGSize:CGSizeMake(1, 1)]};[appearance setTitleTextAttributes:textAttributes2 forState:0];

4.UIBarbutton
注意：UIBarbutton有leftBarButton，rightBarButton和backBarButton，其中backBarButton由于带有箭头，需要单独设置。

barButton背景设置是ios6.0及以后的，而backbutton是ios5.0及以后的，这里要注意！

代码如下：

//修改导航条上的UIBarButtonItemUIBarButtonItem *appearance = [UIBarButtonItem appearanceWhenContainedIn:[UINavigationBar class], nil];//设置导航栏的字体包括backBarButton和leftBarButton，rightBarButton的字体NSDictionary *textAttributes = @{UITextAttributeFont: [UIFont systemFontOfSize:18],                                 UITextAttributeTextColor: [UIColor blueColor],                                 UITextAttributeTextShadowColor: [UIColor whiteColor],                                 UITextAttributeTextShadowOffset: [NSValue valueWithCGSize:CGSizeMake(1, 1)]};[appearance setTitleTextAttributes:textAttributes forState:1];//forState为0时为下正常状态，为1时为点击状态。//修改leftBarButton，rightBarButton背景效果[appearance setBackgroundImage:[UIImage imageNamed:@"navBarButton.png"]                      forState:UIControlStateNormal                         style:UIBarButtonItemStyleBordered                    barMetrics:UIBarMetricsDefault];[appearance setBackgroundImage:[UIImage imageNamed:@"navBarButton_a.png"]                      forState:UIControlStateHighlighted                         style:UIBarButtonItemStyleBordered                    barMetrics:UIBarMetricsDefault];//backBarButton需要单独设置背景效果。只能在ios6.0以后才能用[appearance setBackButtonBackgroundImage:[UIImage imageNamed:@"nav_bg.png"]                                forState:0                              barMetrics:UIBarMetricsDefault];[appearance setBackButtonBackgroundImage:[UIImage imageNamed:@"work.png"]                                forState:1                              barMetrics:UIBarMetricsDefault];[appearance setBackButtonTitlePositionAdjustment:UIOffsetMake(2, -1)                                   forBarMetrics:UIBarMetricsDefault];

5.工具栏（UIToolbar）

UIToolbar *appearance = [UIToolbar appearance];
//样式和背景二选一即可，看需求了
//样式（黑色半透明，不透明等）设置
[appearance setBarStyle:UIBarStyleBlackTranslucent];
//背景设置
[appearance setBackgroundImage:[UIImage imageNamed:@”toolbarBg.png”]
forToolbarPosition:UIToolbarPositionAny
barMetrics:UIBarMetricsDefault];