一、UIWindow简介
UIWindow是最顶级的界面容器。
UIWindow继承自UIView。
UIWindow的主要功能：
- 作为UIView的最顶级容器，包含应用显示所需要的所有的UIView。
- 传递触摸消息和键盘事件给UIView。
UIWindow添加UIView有两种方式：
- 通过调用addSubView方法。
- 通过设置其特有的rootViewController属性。通过设置该属性为要添加view对应的UIViewController，UIWindow将自动将其view添加到当前window中，同时负责ViewController和view的生命周期。
二、UIWindow的使用
UIWindow通过UIWindowLevel设置window的层级。
例创建UIWindow的子类，实现调出输入密码界面。
#import <UIKit/UIKit.h>
@interface PasswordInputWindow : UIWindow
+ (PasswordInputWindow *)sharedInstance;
- (void)show;
@end
#import "PasswordInputWindow.h"
@implementation PasswordInputWindow{
UITextField *_textField;
}
+(PasswordInputWindow *)sharedInstance{
static id sharedInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedInstance = [[self alloc]initWithFrame:[UIScreen mainScreen].bounds];
});
return sharedInstance;
}
- (instancetype)initWithFrame:(CGRect)frame{
self = [super initWithFrame:frame];
if (self) {
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 yellowColor];
textField.secureTextEntry = YES;
[self addSubview:textField];
UIButton *button = [[UIButton alloc]initWithFrame:CGRectMake(10, 110, 200, 44)];
[button setBackgroundColor:[UIColor redColor]];
button.titleLabel.textColor = [UIColor whiteColor];
[button setTitle:@"登录" forState:UIControlStateNormal];
[button addTarget:self action:@selector(completeButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
[self addSubview:button];
self.backgroundColor = [UIColor yellowColor];
_textField = textField;
}
return self;
}
- (void)show{
[self makeKeyWindow];
self.hidden = NO;
}
- (void)completeButtonPressed:(id)sender{
if ([_textField.text isEqualToString:@"1234"]) {
//正确
[_textField resignFirstResponder];
[self resignKeyWindow];
self.hidden = YES;
}else{
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"密码输入错误" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
[alert show];
}
}
//后台进入时调用
[[PasswordInputWindow sharedInstance] show];
一般，手势解锁页、启动介绍页、应用内的通知提醒、弹窗广告等适合用UIWindow来实现。
