登录状态的判定与处理（优化版）

背景：前几天，写了一个登录状态的判定与处理，感觉写得不是很简洁，而且处理不好很容易出现多次持有，造成登录控制器不能释放的问题。于是在上班的间隙重新写了一个，作为“优化版”。

工具

#import <UIKit/UIKit.h>

@interface UIViewController (LoginStatus)

/**
 适用于：
 跳转前需要检查登录状态，并且处于登录状态或登录成功后由`自己`处理的情况
 
 说明：目前逻辑是当用户处于未登录状态，但点击了需要登录才能跳转的页面时，会先跳转到登录页面；
 如果登录不成功会停留在登录页面，用户可以点击“关闭”来返回当前页面，故只存在登录成功回调
 */
- (void)beforePushCheckLoginStatusWithSuccess:(void (^)(void))successBlock;

@end

#import "UIViewController+LoginStatus.h"

#import "MZAccountManager.h"
#import <objc/runtime.h>

/** 登录状态的判定依据 */
static NSString *const kToken = @"token";
/** 登录控制器的类名 */
static NSString *const kLoginVCClassName = @"LoginViewController";


@interface UIViewController ()

@property (nonatomic, copy) dispatch_block_t successBlock;

@end

@implementation UIViewController (LoginStatus)

- (void)beforePushCheckLoginStatusWithSuccess:(void (^)(void))successBlock {
    
    self.successBlock = successBlock;
    
    // 如果没有登录
    if ([self isEmpty:MZUserManager.token] || [MZUserManager.token isEqualToString:@"##"]) {
        UIViewController *loginVC = [[NSClassFromString(kLoginVCClassName) alloc] init];
        if (loginVC) {
            [MZUserManager addObserver:self forKeyPath:kToken options:NSKeyValueObservingOptionNew context:nil];
            UINavigationController *navVC = [[UINavigationController alloc] initWithRootViewController:loginVC];
            [self presentViewController:navVC animated:YES completion:nil];
        }
    } else {
        !self.successBlock ?: self.successBlock();
    }
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context {
    
    if ([keyPath isEqualToString:kToken]) {
        // 登录成功
        if (![self isEmpty:change[NSKeyValueChangeNewKey]] && ![change[NSKeyValueChangeNewKey] isEqualToString:@"##"]) {
            !self.successBlock ?: self.successBlock();
        }
        [MZUserManager removeObserver:self forKeyPath:kToken];
    }
}


#pragma mark - Private Methods

- (BOOL)isEmpty:(NSString *)scrString {
    return (scrString == nil || scrString.length == 0 || [scrString isKindOfClass:[NSNull class]]);
}

- (dispatch_block_t)successBlock {
    return objc_getAssociatedObject(self, _cmd);
}

- (void)setSuccessBlock:(dispatch_block_t)successBlock {
    objc_setAssociatedObject(self, @selector(successBlock), successBlock, OBJC_ASSOCIATION_COPY);
}


@end

登录控制器的处理

#import "LoginViewController.h"

#import "MZAccountManager.h"

@interface LoginViewController ()



@end

@implementation LoginViewController

#pragma mark - Life Cycle

- (void)viewDidLoad {
    [super viewDidLoad];
    
     NSLog(@"%@创建了&&token=%@", [self.class description], MZUserManager.token);
}


#pragma mark - Private Methods

// 点击登录按钮
- (IBAction)loginAction:(id)sender {
    
    MZUserManager.token = @"点击登录，并且登录成功了";
    [self dismissLoginVC];
}

// 点击关闭按钮
- (IBAction)closeAction:(id)sender {
    
    MZUserManager.token = @"##";
    [self dismissLoginVC];
}

- (void)dismissLoginVC {
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (void)dealloc {
    NSLog(@"%@释放了", self.class);
}


@end

---