相关链接
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，又能最简单的饿实现统一的界面风格。
方法详解：
+ (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];
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，否则可能无效，例如：可以写在appdelegate中的“didFinishLaunchingWithOptions”方法中
+ (id)appearanceWhenContainedIn:(Class<>)ContainerClass,...
这个方法可以设置某个类的改变：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];
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
#pragma mark ======修改导航栏背景及字体======
#pragma mark 设置导航条的背景图
[[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:@"导航条"] forBarMetrics:UIBarMetricsDefault];
#pragma mark 设置导航条的颜色
[[UINavigationBar appearance] setBackgroundColor:[UIColor greenColor]];
#pragma mark 设置导航条的字体
/**
// Keys for Text Attributes Dictionaries
// NSString *const UITextAttributeFont; value: UIFont
// NSString *const UITextAttributeTextColor; value: UIColor
// NSString *const UITextAttributeTextShadowColor; value: UIColor
// NSString *const UITextAttributeTextShadowOffset; value: NSValue wrapping a UIOffset struct.
*/
NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:[UIColor yellowColor],NSForegroundColorAttributeName,[UIFont fontWithName:@ "HelveticaNeue-CondensedBlack" size:18.0],NSFontAttributeName, nil];
[[UINavigationBar appearance] setTitleTextAttributes:dic];
#pragma mark ======标签栏（UITabbar）======
#pragma mark tabBar的背景图片
[[UITabBar appearance] setBackgroundImage:[UIImage imageNamed:@"导航条"]];
#pragma mark 设置选择item的背景图片 图片跟着点击事件进行移动
UIImage *selectBackgroundImage = [[UIImage imageNamed:@"tabBar图标"] resizableImageWithCapInsets:UIEdgeInsetsMake(4, 0, 0, 0)];
[[UITabBar appearance] setSelectionIndicatorImage:selectBackgroundImage];
#pragma mark ======分段控件（UISegmentControl）======
UISegmentedControl *segmentControlAppearance = [UISegmentedControl appearance];
//segment正常背景
[segmentControlAppearance setBackgroundImage:[UIImage imageNamed:@"segmentImage"] forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
//segment选中背景
[segmentControlAppearance setBackgroundImage:[UIImage imageNamed:@"segmentSelectImage"] forState:UIControlStateSelected barMetrics:UIBarMetricsDefault];
//segment左右选中/没选中时的分割线
/**
//BarMetrics表示navigation bar的状态，UIBarMetricsDefault表示portrait状态(44pixel height)，UIBarMetricsLandscapePhone
//表示landscape状态(32pixel heght）
*/
[segmentControlAppearance setDividerImage:[UIImage imageNamed:@"line"] forLeftSegmentState:UIControlStateNormal rightSegmentState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[segmentControlAppearance setDividerImage:[UIImage imageNamed:@"line"] forLeftSegmentState:UIControlStateSelected rightSegmentState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[segmentControlAppearance setDividerImage:[UIImage imageNamed:@"line"] forLeftSegmentState:UIControlStateNormal rightSegmentState:UIControlStateSelected barMetrics:UIBarMetricsDefault];
#pragma mark 点击状态的时候的字体的设置
NSDictionary *textAttributes1 = @{UITextAttributeFont: [UIFont systemFontOfSize:18],
UITextAttributeTextColor: [UIColor blueColor],
UITextAttributeTextShadowColor: [UIColor whiteColor],
UITextAttributeTextShadowOffset: [NSValue valueWithCGSize:CGSizeMake(1, 1)]};
[segmentControlAppearance setTitleTextAttributes:textAttributes1 forState:1];
#pragma mark 正常状态时字体的设置
NSDictionary *textAttributes2 = @{UITextAttributeFont: [UIFont systemFontOfSize:18],
UITextAttributeTextColor: [UIColor whiteColor],
UITextAttributeTextShadowColor: [UIColor blackColor],
UITextAttributeTextShadowOffset: [NSValue valueWithCGSize:CGSizeMake(1, 1)]};
[segmentControlAppearance setTitleTextAttributes:textAttributes2 forState:0];
#pragma mark ======UIBarbutton======
/**
UIBarbutton有leftBarButton，rightBarButton和backBarButton，其中backBarButton由于带有箭头，需要单独设置
*/
#pragma mark 修改导航条上的UIBarButtonItem
UIBarButtonItem *buttonItemAppearance = [UIBarButtonItem appearanceWhenContainedInInstancesOfClasses:@[[UINavigationBar class]]];
//设置导航栏的字体包括backBarButton和leftBarButton,rightBarButton的字体
NSDictionary *textAttributesOne = @{UITextAttributeFont: [UIFont systemFontOfSize:20],
UITextAttributeTextColor: [UIColor orangeColor],
UITextAttributeTextShadowColor: [UIColor whiteColor],
UITextAttributeTextShadowOffset: [NSValue valueWithCGSize:CGSizeMake(1, 1)]};
[buttonItemAppearance setTitleTextAttributes:textAttributesOne forState:0]; //forState为0时为正常状态，为1时为点击状态
NSDictionary *textAttributesTwo = @{UITextAttributeFont: [UIFont systemFontOfSize:20],
UITextAttributeTextColor: [UIColor yellowColor],
UITextAttributeTextShadowColor: [UIColor whiteColor],
UITextAttributeTextShadowOffset: [NSValue valueWithCGSize:CGSizeMake(1, 1)]};
[buttonItemAppearance setTitleTextAttributes:textAttributesTwo forState:1]; //forState为0时为正常状态，为1时为点击状态
#pragma mark 修改leftBarButton,rightBarButton背景效果
[buttonItemAppearance setBackgroundImage:[UIImage imageNamed:@"右边按钮"]
forState:UIControlStateNormal
style:UIBarButtonItemStylePlain
barMetrics:UIBarMetricsDefault];
[buttonItemAppearance setBackgroundImage:[UIImage imageNamed:@"右边按钮"]
forState:UIControlStateHighlighted
style:UIBarButtonItemStylePlain
barMetrics:UIBarMetricsDefault];
#pragma mark backBarButton需要单独设置背景效果。
[buttonItemAppearance setBackButtonBackgroundImage:[UIImage imageNamed:@"返回按钮"]
forState:0
barMetrics:UIBarMetricsDefault];
[buttonItemAppearance setBackButtonBackgroundImage:[UIImage imageNamed:@"返回按钮"]
forState:1
barMetrics:UIBarMetricsDefault];
[buttonItemAppearance setBackButtonTitlePositionAdjustment:UIOffsetMake(2, -1)
forBarMetrics:UIBarMetricsDefault];
#pragma mark ======工具栏（UIToolbar）======
UIToolbar *toolbarAppearance = [UIToolbar appearance];
/**
样式和背景二选一即可，看需求
样式(黑色半透明，不透明等)设置
*/
// [toolbarAppearance setBarStyle:UIBarStyleBlackTranslucent];
//背景设置
[toolbarAppearance setBackgroundImage:[UIImage imageNamed:@"导航条"]
forToolbarPosition:UIToolbarPositionAny
barMetrics:UIBarMetricsDefault];
return YES;
}