使用场景

有的时候，比如在当前的页面加载一个游戏，跳转到其他页面显示新闻。会导致之前的页面暂停。因为需要页面不跳转的方式显示新的页面内容。

使用

@interface SecondViewController : UIViewController
@property (nonatomic, copy) void (^goBack)(void);
@end
#import "SecondViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    self.view.backgroundColor = [UIColor blueColor];
    
    UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
    [btn setTitle:@"返回" forState:UIControlStateNormal];
    [self.view addSubview:btn];
    btn.frame = CGRectMake(20, 50, 100, 40);
    btn.backgroundColor = [UIColor grayColor];
    [btn addTarget:self action:@selector(clickGoBack) forControlEvents:UIControlEventTouchUpInside];
}

- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    NSLog(@"%@  %s",self, __func__);
}

- (void)clickGoBack{
    if(self.goBack){
        self.goBack();
    }
}

-(void)dealloc{
    NSLog(@"%@  %s",self, __func__);
}

#import "ViewController.h"
#import "SecondViewController.h"
@interface ViewController ()
@property (nonatomic, strong) SecondViewController *secondVC;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
    [btn setTitle:@"下一页" forState:UIControlStateNormal];
    [self.view addSubview:btn];
    btn.frame = CGRectMake(20, 50, 100, 40);
    btn.backgroundColor = [UIColor grayColor];
    [btn addTarget:self action:@selector(clickGoNext1) forControlEvents:UIControlEventTouchUpInside];
    
}

- (void)clickGoNext1{
    SecondViewController *vc1 = [SecondViewController new];
    [self addChildViewController:vc1];
    [self.view addSubview:vc1.view];
    
    __weak typeof(self) weakSelf = self;
    vc1.goBack = ^{
        __strong typeof(self) self = weakSelf;
        UIViewController *secondVC = [self.childViewControllers firstObject];
        [secondVC.view removeFromSuperview];
        [secondVC removeFromParentViewController];
    };
}

- (void)clickGoNext{
    __weak typeof(self) weakSelf = self;
    SecondViewController *vc = [SecondViewController new];
    [self.view addSubview:vc.view];
    self.secondVC = vc;
    self.secondVC.goBack = ^{
        __strong typeof(self) self = weakSelf;
        [self.secondVC.view removeFromSuperview];
        self.secondVC = nil;
    };
}
@end

其中clickGoNext的方式是我们手动添加一个引用，而clickGoNext1则是通过系统方法帮我们添加了一个引用。本身并无好差之分，可以根据自己的实际情况选择。

另外，上面两种方式都会影响View的生命周期函数被调用viewWillAppear。

如果页面无需关系这些函数，也可以不用视图控制器，直接初始化一个UIView添加到当前的页面中。