iOS App非激活状态的信息保护

越来越多App开始注重对于信息的保护，如支付宝、掌上生活等App在退到后台（回到桌面或者切换App），会加上一个保护层，如下图支付宝的界面：

支付宝保护界面

这个其实很简单，我们只需要在AppDelegate的applicationDidEnterBackground方法中添加一个保护界面，在applicationDidBecomeActive方法中把这个保护界面移除掉就，就初步实现了保护的效果。

初步封装了一个类来实现，代码如下：

JQBackgroundSafeView.h

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@interface JQBackgroundSafeView : UIView



/**
 请在 AppDelegate 中的 didFinishLaunchingWithOptions调用
 */
+ (void)initSafeView;

/**
 请在 AppDelegate 中的 applicationDidEnterBackground调用
 */
+ (void)addSafeView;

/**
 请在 AppDelegate 中的 applicationDidBecomeActive调用
 */
+ (void)removeSafeView;

@end

NS_ASSUME_NONNULL_END

JQBackgroundSafeView.m

#import "JQBackgroundSafeView.h"

@interface JQBackgroundSafeView ()

@property (nonatomic,assign) BOOL isFinishLaunching;

@property (nonatomic,strong) UIView *safeView;

@end

@implementation JQBackgroundSafeView


+ (instancetype)shareInstance
{
    static JQBackgroundSafeView *_mySingle = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        
        _mySingle = [[JQBackgroundSafeView alloc] initWithFrame:UIScreen.mainScreen.bounds];
        [_mySingle setBackgroundColor:[UIColor clearColor]];
        UIBlurEffect *blurEffect =[UIBlurEffect effectWithStyle:UIBlurEffectStyleRegular];
        UIVisualEffectView *effectView =[[UIVisualEffectView alloc]initWithEffect:blurEffect];
        effectView.frame = UIScreen.mainScreen.bounds;
        [_mySingle addSubview:effectView];
        
        
    });
    return _mySingle;
}

+ (void)initSafeView {
    [JQBackgroundSafeView shareInstance].isFinishLaunching = YES;
}

+ (void)addSafeView {
    if (![JQBackgroundSafeView shareInstance].isFinishLaunching) {
        [[[UIApplication sharedApplication] keyWindow] addSubview:[JQBackgroundSafeView shareInstance]];
    }
}

+ (void)removeSafeView {
    [JQBackgroundSafeView shareInstance].isFinishLaunching = NO;
    [[JQBackgroundSafeView shareInstance] removeFromSuperview];
}

@end

实现的话，如JQBackgroundSafeView.h的注释写的那样，只要在AppDalegate中调用JQBackgroundSafeView的类方法即可：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    [JQBackgroundSafeView initSafeView];
    return YES;
}

- (void)applicationDidEnterBackground:(UIApplication *)application {
    
    [JQBackgroundSafeView addSafeView];
}

- (void)applicationDidBecomeActive:(UIApplication *)application {
    
    [JQBackgroundSafeView removeSafeView];
}

这里只是实现了一个毛玻璃效果保护页，如果想要实现其他效果的话就稍微修改下即可。