前面写了UIWindow、UIViewController，那些都是一些框架，框架需要填充上具体的view才能组成我们的应用，移动应用开发中UI占了很大一部分，最基础的UI实现是使用系统提供的各种控件，其他的就是自定义实现了，作者目前是入门状态，只能写写基础控件了。

      iOS中提供了UIButton、UILable、UITextField、UIImageView等基础UI控件，继承于UIView。这里先拿UIButton练练手，为什么拿UIButton呢，因为UIbutton继承自UIControl，UIControl派生自UIView类，每个控件都有很多视图的特性，包括附着于其他视图的能力，所有控件都拥有一套共同的属性和方法，包含显示内容，点击事件等等，UIControl的子类都有事件处理能力。

图、UIControl

UIButton的定义：

     UIButton可使用 initWithFrame、buttonWithType两种方式创建：

1）initWithFrame

  UIButton *btn=[[UIButton alloc]initWithFrame:CGRectMake(60, 60, 200, 60)];     btn.backgroundColor=[UIColor greenColor];     [btn setTitle:@"btn1" forState:UIControlStateNormal];     [self.view addSubview:btn];

2）buttonWithType

UIButton *btn2=[UIButton buttonWithType:UIButtonTypeRoundedRect];     CGRect rect=CGRectMake(60, 160, 200, 60);     btn2.frame=rect;     btn2.tag=1001;     btn2.backgroundColor=[UIColor colorWithRed:30/255.0 green:200/255.0 blue:125/255.0 alpha:1.0];     [btn2 setTitle:@"btn2" forState:UIControlStateNormal];      [btn2 addTarget:self action:@selector(btn2Pressed) forControlEvents:UIControlEventTouchDown];     [self.view addSubview:btn2]; 

-(void)btn2Pressed{      NSLog(@"button pressed"); }

UIButtonType:

typedef enum {     UIButtonTypeCustom = 0,           // no button type   自定义，无风格     UIButtonTypeRoundedRect,          // rounded rect, flat white button, like in address card 白色圆角矩形，类似偏好设置表格单元或者地址簿卡片     UIButtonTypeDetailDisclosure,//蓝色的披露按钮，可放在任何文字旁     UIButtonTypeInfoLight,//微件(widget)使用的小圆圈信息按钮，可以放在任何文字旁     UIButtonTypeInfoDark,//白色背景下使用的深色圆圈信息按钮     UIButtonTypeContactAdd,//蓝色加号(+)按钮，可以放在任何文字旁 } UIButtonType;

UIButton常用属性：

//设置对应状态的标题内容default is nil. title is assumed to be single line

- (void)setTitle:(NSString *)title forState:(UIControlState)state;  

//设置对应状态的标题颜色           

- (void)setTitleColor:(UIColor *)color forState:(UIControlState)state;   

//设置对应状态的标题阴影颜色            

- (void)setTitleShadowColor:(UIColor *)color forState:(UIControlState)state;          

//设置对应状态的按钮的图片

- (void)setImage:(UIImage *)image forState:(UIControlState)state;        

//设置对应状态的按钮背景图片

- (void)setBackgroundImage:(UIImage *)image forState:(UIControlState)state;    

UIButton的UIControlState   ：     

typedef NS_OPTIONS(NSUInteger, UIControlState) {     UIControlStateNormal       = 0,     UIControlStateHighlighted  = 1 << 0,                  // used when UIControl isHighlighted is set     UIControlStateDisabled     = 1 << 1,     UIControlStateSelected     = 1 << 2,                  // flag usable by app (see below)     UIControlStateApplication  = 0x00FF0000,              // additional flags available for application use     UIControlStateReserved     = 0xFF000000               // flags reserved for internal framework use };

更多属性可参考官方文档。

UIButton添加事件：

[btn addTarget:<#(id)#> action:<#(SEL)#> forControlEvents:<#(UIControlEvents)#>]

typedef NS_OPTIONS(NSUInteger, UIControlEvents) {     UIControlEventTouchDown           = 1 <<  0,      // on all touch downs     UIControlEventTouchDownRepeat     = 1 <<  1,      // on multiple touchdowns (tap count > 1)     UIControlEventTouchDragInside     = 1 <<  2,     UIControlEventTouchDragOutside    = 1 <<  3,     UIControlEventTouchDragEnter      = 1 <<  4,     UIControlEventTouchDragExit       = 1 <<  5,     UIControlEventTouchUpInside       = 1 <<  6,     UIControlEventTouchUpOutside      = 1 <<  7,     UIControlEventTouchCancel         = 1 <<  8,      UIControlEventValueChanged        = 1 << 12,     // sliders, etc.      UIControlEventEditingDidBegin     = 1 << 16,     // UITextField     UIControlEventEditingChanged      = 1 << 17,     UIControlEventEditingDidEnd       = 1 << 18,     UIControlEventEditingDidEndOnExit = 1 << 19,     // 'return key' ending editing      UIControlEventAllTouchEvents      = 0x00000FFF,  // for touch events     UIControlEventAllEditingEvents    = 0x000F0000,  // for UITextField     UIControlEventApplicationReserved = 0x0F000000,  // range available for application use     UIControlEventSystemReserved      = 0xF0000000,  // range reserved for internal framework use     UIControlEventAllEvents           = 0xFFFFFFFF };

参考：

http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UIButton_Class/UIButton/UIButton.html

一、UIKit结构图

     本文转自xyz_lmn51CTO博客，原文链接：http://blog.51cto.com/xyzlmn/1230732，如需转载请自行联系原作者