手工创建UIWindow

手工创建UIWindow,可以在应用开发中将某些界面覆盖到最上层

/* eg.支付宝客户端的手势解锁功能\ 密码保护输入界面\ 应用的启动介绍页\ 应用内的通知提醒显示\ 应用内的弹框广告等

// 如果我们创建的 UIWindow 需要处理键盘事件,那就需要将其合理的设置为 keyWindow. keyWindow是被系统设计用来接收键盘和其他非触摸事件的 UIWindow.我们可以通过makeKeyWindow 和 resignKeyWindow来将自己创建的UIWindow 设置成keyWindow.但不要滥用

---

示例代码: 实现一个继承自 UIWindow 的子类 PasswordInputWindow ,完成密码输入界面的显示和处理逻辑..

// 只需应用进入后台的回调函数调用即可

- (void)applicationDidEnterBackground:(UIApplication *)application {

     [[PasswordInputWindow sharedInstance] show];

}

---

#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;

}

- (void)show{

[self makeKeyWindow];// 如果我们创建的 UIWindow 需要处理键盘事件,那就需要将其合理的设置为 keyWindow. keyWindow是被系统设计用来接收键盘和其他非触摸事件的 UIWindow.我们可以通过makeKeyWindow 和 resignKeyWindow来将自己创建的UIWindow 设置成keyWindow.但不要滥用

self.hidden = NO;

}

- (instancetype)initWithFrame:(CGRect)frame{

if (self = [super initWithFrame:frame]) {

UILabel * label = [[UILabel alloc] initWithFrame:CGRectMake(10, 50, 200, 20)];

label.text = @"清输入密码";

[self addSubview:label];

UITextField * textField = [[UITextField alloc] initWithFrame:CGRectMake(10, 80, 200, 20)];

textField.backgroundColor = [UIColor whiteColor];

textField.secureTextEntry = YES;

[self addSubview:textField];

UIButton * button = [[UIButton alloc] initWithFrame:CGRectMake(10, 110, 200, 44)];

[button setBackgroundColor:[UIColor blueColor]];

button.titleLabel.textColor = [UIColor whiteColor];

[button setTitle:@"确定" forState: UIControlStateNormal];

[button addTarget:self action:@selector(completeButtonClicked:) forControlEvents:UIControlEventTouchUpInside];

[self addSubview:button];

self.backgroundColor = [UIColor lightGrayColor];

_textField = textField;

}

return self;

}

- (void)completeButtonClicked:(id)sender{

if ([_textField.text isEqualToString:@"abcd"]) {

[_textField resignFirstResponder];

[self resignKeyWindow];

self.hidden = YES;

}else{

[self showErrorAlertView];

}

}

- (void)showErrorAlertView{

UIAlertView * alertView = [[UIAlertView alloc] initWithTitle:nil message:@"密码错误" delegate: self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];

[alertView show];

}

@end