iOS开发-UI 从入门到精通(三)是对 iOS开发-UI 从入门到精通(一)知识点的综合练习，搭建一个简单地登陆界面，增强实战经验，为以后做开发打下坚实的基础！

※在这里我们还要强调一下，开发环境和内存管理注意事项（最后一次强调，以后文章中将不会在出现希望大家谨记）：

1、前期iOS-UI开发我们需要手动管理内存，所以我们要把ARC关掉（Xcode关掉ARC的步骤）；

（1）打开Xcode选中当前工程：

（2）选中Build Settings：

（3）在输入框内输入count：

（4）选择Objective-C Automatic Reference Counting  将其设置为  NO：

(5)AppDelegate.h文件中将：@PRoperty (assign, nonatomic) UIWindow *window;改成@property (retain, nonatomic) UIWindow *window;

(6)AppDelegate.m文件中重写：- (void)dealloc　　{　　[_window release];　　[super dealloc];　　}

2、在开发当中我们会用到模拟器下面我们来看一下模拟器添加步骤（Xcode环境下）；

（1）打开Xcode选择Window下的Devices：

（2）点击“+”在弹出来的选择框里对 Simulator Name 进行选择：

一、利用所学的知识搭建一个简单地登陆界面界面呈现“账号”、“密码”、“登录”、“忘记密码”、“注册”等：

AppDelegate.h文件中：

1 #import <UIKit/UIKit.h>
2 
3 @interface AppDelegate : UIResponder <UIapplicationDelegate>
4 
5 @property (retain, nonatomic) UIWindow *window;
6 
7 @end

AppDelegate.m文件中：

 1 @implementation AppDelegate
 2 
 3 - (void)dealloc
 4 {
 5     [_window release];
 6     [super dealloc];
 7 }
 8 
 9 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
10     // Override point for customization after application launch.
11 #pragma mark--:window窗口
12     self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
13     
14     _window.backgroundColor = [UIColor whiteColor];
15     
16 #pragma mark--:创建一个view
17     UIView * view = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
18     
19     view.backgroundColor = [UIColor whiteColor];
20     
21 #pragma mark--:创建两个UILabel(账号\密码)
22     UILabel * numLabel = [[UILabel alloc] initWithFrame:CGRectMake(60, 100, 50, 30)];
23     
24     numLabel.text = @"账  号:";
25     
26     UILabel * passLabel = [[UILabel alloc] initWithFrame:CGRectMake(60, 160, 50, 30)];
27     
28     passLabel.text = @"密  码:";
29     
30 #pragma mark--:创建两个UITextField(账号输入框\密码输入框)
31     UITextField * numTextField = [[UITextField alloc] initWithFrame:CGRectMake(130, 100, 200, 30)];
32     
33     numTextField.borderStyle = UITextBorderStyleRoundedRect;
34     
35     numTextField.placeholder = @"请输入手机号/邮箱";
36     
37     UITextField * passTextField = [[UITextField alloc] initWithFrame:CGRectMake(130, 160, 200, 30)];
38     
39     passTextField.borderStyle = UITextBorderStyleRoundedRect;
40     
41     passTextField.placeholder = @"请输入密码";
42     
43 #pragma mark--:创建三个Button(登录\忘记密码\注册)
44     UIButton * loginBtn = [UIButton buttonWithType:UIButtonTypeSystem];
45     
46     loginBtn.frame = CGRectMake(60, 220, 40, 40);
47     
48     [loginBtn setTitle:@"登录" forState:UIControlStateNormal];
49     
50     UIButton * forgetBtn = [UIButton buttonWithType:UIButtonTypeSystem];
51     
52     forgetBtn.frame = CGRectMake(160, 220, 60, 40);
53     
54     [forgetBtn setTitle:@"忘记密码" forState:UIControlStateNormal];
55     
56     UIButton * regisBtn = [UIButton buttonWithType:UIButtonTypeSystem];
57     
58     regisBtn.frame = CGRectMake(280, 220, 40, 40);
59     
60     [regisBtn setTitle:@"注册" forState:UIControlStateNormal];
61     
62 #pragma mark--:添加到视图上
63     [view addSubview:regisBtn];
64     
65     [view addSubview:forgetBtn];
66     
67     [view addSubview:loginBtn];
68     
69     [view addSubview:passTextField];
70     
71     [view addSubview:numTextField];
72     
73     [view addSubview:passLabel];
74     
75     [view addSubview:numLabel];
76     
77     [_window addSubview:view];
78     
79     [_window makeKeyAndVisible];
80     
81 #pragma mark--:释放
82     [passTextField release];
83     
84     [numTextField release];
85     
86     [passLabel release];
87     
88     [numLabel release];
89     
90     [view release];
91     
92     [_window release];
93 
94     return YES;
95 }
96 
97 @end

模拟器运行效果图：

下一篇将持续更新配套知识点及练习；

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