标签：
UI概述
UI(User Interface):?用户界?面,?用户能看到的各种各样的?页?面元素。
iOS App = 各种各样的UI控件 + 业务逻辑和算法。
什么是window？
- window是窗?口,每个app都需要借助window将内容展现给?用户看。
- 在iOS中,使?用UIWindow类来表?示窗?口,通常?一个应?用程序只创建 ?一个UIWindow对象。
- window的主要作用是呈现内容给用户，我们不会对window做太多操作。
-
如何创建window？
通常window的大小（frame）与屏幕（UIScreen）大小一致。
代码： self.window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];
创建项目流程：
- command+shift+N->iOS下的Application->Empty Application.点击Next。
- 输入Product Name，点击Next。
- 选择项目保存路径，点击Create。
-
什么是View？
view（视图）：代表屏幕上的一个矩形区域。IOS中用UIView来表示视图。
不同的控件代表不同种类的view。
创建视图的步骤如下:
- 开辟空间并初始化视图（初始化时，给出视图位置和大小）
- 对视图做一些设置（比如：背景颜色）
- 将视图添加到window上进行显示。
- 释放视图对象。
视图创建代码：
[self createView];
-(void)createView{
UIView *blueView = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 120, 100)];
blueView.backgroundColor = [UIColor blueColor];
[self.window addSubview:blueView];
[blueView release];
}
frame
frame是view的重要属性，是我们做视图布局的关键，它决定了视图的大小和位置。
iOS坐标系
ios提供了用于布局的平面坐标系。左上角为坐标系的原点。
水平向右：为x的正方向。屏幕最左到最右可划分320等份。
垂直向下：为y的正方向。屏幕最上到最下可划分为480等份（3.5存屏幕）。
坐标系不是以像素作为划分依据，而是以“点”作为依据。
frame是一个结构体，包含2部分内容：origin和size；
origin也是一个结构体，包含2部分内容：x和y
size同样是一个结构体，包含2部分内容：width和height；
frame的origin和size是相对于俯视图来说的
CGRectMake（）函数可以帮我们快速构造一个CGRect变量。
center
center（中心点)也是view重要的属性
center是个结构体，包含2个部分：x和y。
center与frame有着密切的联系。
center.x = frame.origin.x+frame.size.width/2;
center.y = frame.origin.y+frame.size.height/2;
bounds
bounds(边界）也是view的重要属性，用于定义自己的边界。它同frame一样是一个CGRect结构体变量。
当一个view设置bounds时，会把自己当成一个容器，定义自己的边界大小以及左上角的初始坐标。
当子视图添加到此视图时，会根据bounds指定的原点(0,0)计算frame，而非左上角。
bounds、frame、center关系
添加视图
管理视图层次
视图重要属性
UILabel
UILabel（标签）：是显示文本的控件。在App中UILabel是出现频率最高的空间。
UILabel是UIView子类，作为子类一般是为了扩充父类的功能，UILabel扩展了文字显示的功能，UILabel是能显示文字的视图。
实例讲解：
#import "AppDelegate.h"
@interface AppDelegate ()
@end
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen]bounds]];
self.window.backgroundColor = [UIColor grayColor];
[self.window makeKeyAndVisible];
// [self createView];
// [self createView1];
// [self createView2];
// [self createLabel];
[self createView3];
// Override point for customization after application launch.
return YES;
}
-(void)createView{
UIView *View1 = [[UIView alloc]initWithFrame:CGRectMake(100, 100, 150, 150)];
View1.backgroundColor = [UIColor redColor];
[self.window addSubview:View1];
UIView *View2 = [[UIView alloc]initWithFrame:CGRectMake(120, 120, 150, 150)];
View2.backgroundColor = [UIColor purpleColor];
[self.window addSubview:View2];
UIView *view3 = [[UIView alloc]initWithFrame:CGRectMake(130, 130, 140, 140)];
view3.backgroundColor = [UIColor grayColor];
[self.window addSubview:view3];
}
-(void)createView1{
UIView *aview = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 100, 100)];
aview.backgroundColor = [UIColor redColor];
UIView *bview = [[UIView alloc]initWithFrame:CGRectMake(20, 20, 100, 100)];
bview.backgroundColor = [UIColor grayColor];
UIView *cview = [[UIView alloc]initWithFrame:CGRectMake(40, 40, 100, 100)]; cview.backgroundColor = [UIColor greenColor]; UIView *dview = [[UIView alloc]initWithFrame:CGRectMake(60, 60, 100, 100)]; dview.backgroundColor = [UIColor purpleColor]; UIView *eview = [[UIView alloc]initWithFrame:CGRectMake(80, 80, 100, 100)]; eview.backgroundColor = [UIColor yellowColor]; [self.window addSubview:aview]; [self.window addSubview:bview]; [self.window insertSubview:cview atIndex:1]; [self.window insertSubview:dview aboveSubview:aview]; [self.window insertSubview:eview belowSubview:bview]; [self.window bringSubviewToFront:aview]; [self.window sendSubviewToBack:aview]; [self.window exchangeSubviewAtIndex:0 withSubviewAtIndex:3]; [self.window removeFromSuperview];
}
-(void)createView2{
UIView *view4= [[UIView alloc]initWithFrame:CGRectMake(50, 50, 200, 200)];
view4.backgroundColor = [UIColor purpleColor];
UIView *view5 = [[UIView alloc]initWithFrame:CGRectMake(100, 100, 200, 200)];
view5.backgroundColor = [UIColor blueColor];
[self.window addSubview:view4];
[view4 addSubview:view5];
view4.hidden = YES;
view4.hidden = NO;
view4.alpha = 1;
UIView *superView = [view4 superview];
NSLog(@"%@",superView);
NSArray *subViews = [view4 subviews];
NSLog(@"%@",subViews);
view4.tag = 105;
UIView *view = [superView viewWithTag:105];
NSLog(@"%@",view);
}
-(void)createLabel{
UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(50, 50, 150, 150)];
label.backgroundColor = [UIColor redColor];
[self.window addSubview:label];
label.text = @"I love you my love yanyan";
label.textColor = [UIColor purpleColor];
label.textAlignment = NSTextAlignmentCenter;
label.font = [UIFont fontWithName:@"Helvetica-Bold" size:25];
label.numberOfLines = 4;
label.lineBreakMode = NSLineBreakByWordWrapping;
label.shadowColor = [UIColor yellowColor];
label.shadowOffset = CGSizeMake(2,1);
}
-(void)createView3{
UIView *V1 = [[UIView alloc]initWithFrame:CGRectMake(35, 190, 100 ,35 )];
V1.backgroundColor = [UIColor redColor];
UIView *V2 = [[UIView alloc]initWithFrame:CGRectMake(160, 190, 180, 35)]; V2.backgroundColor = [UIColor blueColor]; UIView *V3 = [[UIView alloc]initWithFrame:CGRectMake(35, 250, 100 ,35 )]; V3.backgroundColor = [UIColor redColor]; UIView *V4 = [[UIView alloc]initWithFrame:CGRectMake(160, 250, 180, 35)]; V4.backgroundColor = [UIColor blueColor]; UIView *V5 = [[UIView alloc]initWithFrame:CGRectMake(35, 310, 85, 35)]; V5.backgroundColor = [UIColor greenColor]; UIView *V6 = [[UIView alloc]initWithFrame:CGRectMake(145, 310, 85, 35)]; V6.backgroundColor = [UIColor greenColor]; UIView *V7 = [[UIView alloc]initWithFrame:CGRectMake(255, 310, 85, 35)]; V7.backgroundColor = [UIColor greenColor]; [self.window addSubview:V1]; [self.window addSubview:V2]; [self.window addSubview:V3]; [self.window addSubview:V4]; [self.window addSubview:V5]; [self.window addSubview:V6]; [self.window addSubview:V7]; }- (void)applicationWillResignActive:(UIApplication *)application { // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state. // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.}- (void)applicationDidEnterBackground:(UIApplication *)application { // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later. // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.}- (void)applicationWillEnterForeground:(UIApplication *)application { // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.}- (void)applicationDidBecomeActive:(UIApplication *)application { // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.}- (void)applicationWillTerminate:(UIApplication *)application { // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.}
@end
UIView及其子类 UILabel
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原文地址：http://www.cnblogs.com/YDBBK/p/4790946.html
