1、作为容器,包含app所要显示的所有视图
3、与UIViewController协同工作,方便完成设备方向旋转的支持
1、addSubview
2、rootViewController
三、WindowLevel
const UIWindowLevel UIWindowLevelNormal;
const UIWindowLevel UIWindowLevelAlert;
const UIWindowLevel UIWindowLevelStatusBar;
typedef CGFloat UIWindowLevel;
CGFloat _windowSublevel;),不过系统并没有把则个属性开出来。UIWindow的默认级别是UIWindowLevelNormal,我们打印输出这三个level的值分别如下:
46:08.752 UIViewSample[395:f803] Normal window level: 0.000000
2012-03-27 22:46:08.754 UIViewSample[395:f803] Normal window level: 2000.000000
2012-03-27 22:46:08.755 UIViewSample[395:f803] Normal window level: 1000.000000
这样印证了他们级别的高低顺序从小到大为Normal < StatusBar < Alert,下面请看小的测试代码:
TestWindowLevel
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
self.window.backgroundColor = [UIColor yellowColor];
[self.window makeKeyAndVisible];
UIWindow \*normalWindow = \[\[UIWindow alloc\] initWithFrame:\[\[UIScreen mainScreen\] bounds\]\];
normalWindow.backgroundColor = \[UIColor blueColor\];
normalWindow.windowLevel = UIWindowLevelNormal;
\[normalWindow makeKeyAndVisible\];
CGRect windowRect = CGRectMake(50,
50,
\[\[UIScreen mainScreen\] bounds\].size.width - 100,
\[\[UIScreen mainScreen\] bounds\].size.height - 100);
UIWindow \*alertLevelWindow = \[\[UIWindow alloc\] initWithFrame:windowRect\];
alertLevelWindow.windowLevel = UIWindowLevelAlert;
alertLevelWindow.backgroundColor = \[UIColor redColor\];
\[alertLevelWindow makeKeyAndVisible\];
UIWindow \*statusLevelWindow = \[\[UIWindow alloc\] initWithFrame:CGRectMake(0, 50, 320, 20)\];
statusLevelWindow.windowLevel = UIWindowLevelStatusBar;
statusLevelWindow.backgroundColor = \[UIColor blackColor\];
\[statusLevelWindow makeKeyAndVisible\];
NSLog(@"Normal window level: %f", UIWindowLevelNormal);
NSLog(@"Normal window level: %f", UIWindowLevelAlert);
NSLog(@"Normal window level: %f", UIWindowLevelStatusBar);
return YES;
}
1)我们生成的normalWindow虽然是在第一个默认的window之后调用makeKeyAndVisible,但是仍然没有显示出来。这说明当Level层级相同的时候,只有第一个设置为KeyWindow的显示出来,后面同级的再设置KeyWindow也不会显示。
2)statusLevelWindow在alertLevelWindow之后调用makeKeyAndVisible,淡仍然只是显示在alertLevelWindow的下方。这说明UIWindow在显示的时候是不管KeyWindow是谁,都是Level优先的,即Level最高的始终显示在最前面。
有时候,我们也希望在应用开发中,将某些界面覆盖在所有界面最上层。这个时候,我们就可以手工创建一个新的UIWindow。例如,想做一个密码保护功能,在用户从应用的任何界面按Home键退出,过段时间再从后台切换回来时,显示一个密码输入界面。
Demo界面很简单,每次启动应用或者从后台进入应用,都会显示输入密码界面,只有密码输入正确,才能使用应用。
大致代码如下:
PasswordInputWindow.h 文件。 定义一个继承自UIWindow的子类 PasswordInputWindow, shareInstance 是单例, show方法就是用来显示输入密码界面。
@interface PasswordInputView : UIWindow
(PasswordInputView *)shareInstance;
(void)show;
PasswordInputWindow.m 文件。
#import "PasswordInputView.h"
@interface PasswordInputView()
@property (nonatomic,weak) UITextField *textField;
@end
@implementation PasswordInputView
#pragma mark - Singleton
(PasswordInputView *)shareInstance {
static id instance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[self alloc] initWithFrame:[UIScreen mainScreen].bounds];
});
return instance;
}
#pragma mark - Initilize
(instancetype)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) {
[self setup];
}
return self;
}
(instancetype)initWithCoder:(NSCoder *)decoder {
if (self = [super initWithCoder:decoder]) {
[self setup];
}
return self;
}
(void)setup {
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(10, 50, 200, 20)];
label.text = @"请输入密码";
[self addSubview:label];
UITextField *textField = [[UITextField alloc] initWithFrame:CGRectMake(10, 80, 200, 20)];
textField.backgroundColor = [UIColor whiteColor];
textField.secureTextEntry = YES;
[self addSubview:textField];
self.textField = textField;
UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(10, 110, 200, 44)];
[button setBackgroundColor:[UIColor blueColor]];
[button setTitle:@"确定" forState:UIControlStateNormal];
[button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[button addTarget:self action:@selector(completeButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
[self addSubview:button];
self.backgroundColor = [UIColor yellowColor];
}
#pragma mark - Common Methods
(void)completeButtonPressed:(UIButton *)button {
if ([self.textField.text isEqualToString:@"123456"]) {
[self.textField resignFirstResponder];
[self resignKeyWindow];
self.hidden = YES;
} else {
[self showErrorAlertView];
}
}
(void)showErrorAlertView {
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:nil message:@"密码错误,请重新输入" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
[alertView show];
}
(void)show {
[self makeKeyWindow];
self.hidden = NO;
}
1.代码中我实现了initWithFrame和initWithCoder两个方法,这样可以保证,不管用户是纯代码还是xib实现的初始化,都没有问题。
2.如果我们创建的UIWindow需
要处理键盘事件,那就要合理的将其设置为keyWindow。keyWindow是被系统设计用来接受键盘和其他非触摸事件的UIWindow。我们可以
通过makeKeyWindow 和 resignKeyWindow 方法来将自己创建的UIWindow实例设置成keyWindow。
3. 加入以下代码,就可以保证,程序每次从后台进入的时候,先显示输入密码界面了。
- (void)applicationDidBecomeActive:(UIApplication *)application {
[[PasswordInputView shareInstance] show];
}
手机扫一扫
移动阅读更方便
你可能感兴趣的文章