iOS 模态窗口居中弹出背景半透明

实现功能：点击UIImageView弹出一个模态窗口并居中显示，背景为灰色半透明

App中有很多地方用到点击用户头像并弹出一个模态窗体，显示该用户的一些信息，考虑到很多地方使用，就写了一个UIImageView的类别，将点击手势封装到这个类别中，已达到共用代码的效果。github上有很多模态窗体库

实现思路：先将当前视图控制器的视图设置为透明[self.view.backgroundColor clearColor]，然后将一个灰色半透明UIView(grayAlphaView)添加到self.view
, [self.view addSubview:grayAlphaView];  再将一个容器视图containerView(UIView) 添加到灰色半透明视图上grayAlphaView
[grayAlphaView addSubview:containerView];

1.UIImageView+UserHeadTap

@interface UIImageView (UserHeadTap)

- (id) initWithTap;

@end

#import "UIImageView+UserHeadTap.h"
#import "NameCardViewController.h"
#import "UIViewController+Utils.h"

@implementation UIImageView (UserHeadTap)

- (id) initWithTap {
    if (self = [super init]) {
        self.userInteractionEnabled = YES;
        UITapGestureRecognizer * tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(userHeaderTapAction:)];
        [self addGestureRecognizer:tapGestureRecognizer];
    }
    
    return self;
}

- (void) userHeaderTapAction:(UITapGestureRecognizer *)tapGestureRecognizer {
    UIViewController * parentViewController = [UIViewController currentViewController];

    NameCardViewController * controller = [[NameCardViewController alloc] init];
    controller.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
    if ([[UIDevice currentDevice].systemVersion floatValue] >= 8.0) {
        controller.providesPresentationContextTransitionStyle = YES;
        controller.definesPresentationContext = YES;
        controller.modalPresentationStyle = UIModalPresentationOverCurrentContext;
        [parentViewController presentViewController:controller animated:YES completion:nil];
    } else {
        parentViewController.view.window.rootViewController.modalPresentationStyle = UIModalPresentationCurrentContext;
        [parentViewController presentViewController:controller animated:NO completion:nil];
        parentViewController.view.window.rootViewController.modalPresentationStyle = UIModalPresentationFullScreen;
    }
}

@end

2.ViewController

#import "UIViewController+Utils.h"
@implement ViewController 

- (void)viewDidLoad {
     UIImageView * userHeadImageView = [UIImageView initWithTap];
     userHeadImageView.frmae = CGRectMake(50, 50, 70, 70);
     userHeadImageView.image = [UIImage imageNamed:@"icon"];

     [self.view addSubview:userHeadImageView];
}

@end

3. NameCardViewController(名片)

#import "NameCardViewController.h"

@interface NameCardViewController ()

@end

@implementation NameCardViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor clearColor];
    
    UIView *grayAlphaView = [[UIView alloc] initWithFrame:self.view.frame];
    grayAlphaView.backgroundColor = [UIColor grayColor];
    grayAlphaView.alpha = 0.8;
    [self.view addSubview:grayAlphaView];
    
    UIView *containerView = [[UIView alloc] init];
    containerView.size = CGSizeMake(self.view.size.width - 40 * 2, 350);
    containerView.center = self.view.center;
    containerView.backgroundColor = [UIColor redColor];

    [grayAlphaView addSubview:containerView];
}

@end

4. 实现效果如果

该效果还没有实现全屏