swift 懒加载，重写model的set方法赋值，按钮点击，d

1.懒加载

private lazy var label : UILabel = {
       
        let label = UILabel()
        label.textColor = UIColor.blackColor()
        label.textAlignment = NSTextAlignment.Center
        label.font = UIFont.systemFontOfSize(18)
        
        return label
    }()

2.重写model的set方法赋值（可选类型要先判断为不为nil，为nil强转会崩）

var model : WBModel? {
        
        didSet {
            label.text = model!.title
            
            //如果拼接的话要转
            if let string = model?.title {
                label.text = "cell  \(string)"
            }
        }
        
    }

3.按钮的点击 ：

无参数Selector("btnWithLogin”) 或者 #selector(LoginViewController.btnWithLogin)

有参数Selector(“btnWithLogin:”)
#selector(MyDetailHeardView.btnWithLogin(_:))

btn_sure.addTarget(self, action: Selector(“btnWithLogin:"), forControlEvents: UIControlEvents.TouchUpInside)

注意：@objc别忘了这个！！！！！！
@objc private func btnWithLogin(btn : UIButton) -> Void {
        
        if delegate != nil {
            delegate?.myDetailHeardViewDidClick(btn.tag)
        }
    }

4.代理delegate

1.定义
protocol LoginInputViewDelegate : NSObjectProtocol {
    
    func didClickWithForget()
}

class LoginInputView: UIView {
    
    
    weak var delegate : LoginInputViewDelegate?
    
    //MARK: - 点击了忘记密码，别忘了@objc
    @objc private func btnWithForget() -> Void {
        
        if delegate != nil {
            delegate?.didClickWithForget()
        }
    }

    private lazy var btn_forget : UIButton = {
       
        let btn_forget = UIButton(type: UIButtonType.Custom)
        btn_forget.addTarget(self, action: #selector(LoginInputView.btnWithForget), forControlEvents: UIControlEvents.TouchUpInside)
        
        return btn_forget
    }()
}

2.实现
extension LoginViewController : LoginInputViewDelegate {
    
    func didClickWithForget() {
        print("点击了忘记密码")
    }
    
}

5.重写frame的set方法,注意：如果头部要出现空隙，y+的同时，height要-

    //重写frame
    override var frame:CGRect{
        didSet {
            
            var newFrame = frame
            newFrame.origin.x += 10/2
            newFrame.size.width -= 10
            newFrame.origin.y += 10
            newFrame.size.height -= 10
            super.frame = newFrame
            
            
        }
    }

6. 移除通知

deinit
    {
        NSNotificationCenter.defaultCenter().removeObserver(self)
    }

7.下载图片dispatch_group_create用法

private func cachesImages(viewModels: [StatusViewModel])
    {
        // 0.创建一个组
        let group = dispatch_group_create()
        
        for viewModel in viewModels
        {
            // 1.从模型中取出配图数组
            guard let picurls = viewModel.thumbnail_pic else
            {
                 // 如果当前微博没有配图就跳过, 继续下载下一个模型的
                continue
            }
            // 2.遍历配图数组下载图片
            for url in picurls
            {
                // 将当前的下载操作添加到组中
                dispatch_group_enter(group)
                
                // 3.3利用SDWebImage下载图片
                
                SDWebImageManager.sharedManager().downloadImageWithURL(url, options: SDWebImageOptions(rawValue: 0), progress: nil, completed: { (image, error, _, _, _) -> Void in
                    NJLog("图片下载完成")
                    // 将当前下载操作从组中移除
                    dispatch_group_leave(group)
                })
            }
        }
        
        // 监听下载操作
        dispatch_group_notify(group, dispatch_get_main_queue()) { () -> Void in
            NJLog("全部下载完成")
            self.statuses = viewModels
        }
    }