keyWindow与delegate中Window的区别

keyWindow与delegate中Window的区别

keyWindow与delegate中Window的区别

源码:

//
//  ViewController.m
//  UIWindowRelated
//
//  Created by YouXianMing on 14/10/25.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    NSLog(@"-------");
    NSLog(@"%@", [UIApplication sharedApplication].keyWindow);
    NSLog(@"%@", [[[UIApplication sharedApplication] delegate] window]);
}

- (void)viewDidAppear:(BOOL)animated {
    NSLog(@"#######");
    NSLog(@"%@", [UIApplication sharedApplication].keyWindow);
    NSLog(@"%@", [[[UIApplication sharedApplication] delegate] window]);
}

@end

结果如下图:

keyWindow与delegate中Window的区别

从打印结果中可以知道:

keyWindow与delegate中的window其实是一样的,keyWindow的存在的意义,其实就是为了说明当前的window接管了这个控制器的view而已,你可以在keyWindow上加载你自己的建立的view了。

现在提供一个便利的类目^_^:

//
//  UIWindow+Window.h
//  Window
//
//  Created by YouXianMing on 14-10-10.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface UIWindow (Window)

/**
 *  返回keyWindow(如果keyWindow有值,代表着你可以给window添加view了)
 *
 *  @return 可以添加view并显示出来的window(如果返回为nil,说明你不能将view添加到window上去显示)
 */
+ (UIWindow *)usableWindow;

/**
 *  返回window
 *
 *  @return window(你给这个window添加的view很有可能被控制器的view覆盖而显示不了)
 */
+ (UIWindow *)rootWindow;

@end
//
//  UIWindow+Window.m
//  Window
//
//  Created by YouXianMing on 14-10-10.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//

#import "UIWindow+Window.h"

@implementation UIWindow (Window)

+ (UIWindow *)usableWindow
{
    return [UIApplication sharedApplication].keyWindow;
}

+ (UIWindow *)rootWindow
{
    return [[[UIApplication sharedApplication] delegate] window];
}

@end

 

keyWindow与delegate中Window的区别

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