概述

由于讨厌系统自带的alertView只能通过点击按钮才能关闭。你说万一按钮区域都是功能性的操作呢（这可不是我胡思乱想哦，要怪就产品的想法吧，呵呵哒），所以我们还是应该备有一个带有“X”（关闭按钮，为什么是叫X，因为X这个标志很明显嘛~）的alertView。

详细

代码下载：http://www.demodashi.com/demo/10917.html

一、程序实现

1、程序结构

2、实现思路与代码

XBAlertView是作为显示弹出框的入口，在初始化XBAlertView示例时，会将弹出框除了按钮部分全都设置好。而按钮部分采用UICollectionView来实现（因为有可能有多个按钮，这样方便扩展）。

- (void)setupContentView{
    //title
    self.alertTitleLabel = [[UILabel alloc] init];
    self.alertTitleLabel.font = [UIFont boldSystemFontOfSize:17.0f];
    self.alertTitleLabel.textAlignment = NSTextAlignmentCenter;
    self.alertTitleLabel.frame = CGRectMake(TitleHorizontalOffset, TitleMarginTop, SelfWidth - TitleHorizontalOffset * 2, self.alertTitleLabel.font.lineHeight);
    [self addSubview:self.alertTitleLabel];
    //content
    CGFloat contentLabelWidth = SelfWidth - ContentHorizontalOffset * 2;
    CGFloat contentH = [self heightWithContent:_content byWidth:contentLabelWidth andFontSize:13 andLineSpacing:3];
    self.alertContentLabel = [[UILabel alloc] initWithFrame:CGRectMake(ContentHorizontalOffset, CGRectGetMaxY(self.alertTitleLabel.frame) + ContentMarginTop, contentLabelWidth, contentH)];
    self.alertContentLabel.numberOfLines = 0;
    self.alertContentLabel.textAlignment = NSTextAlignmentCenter;
    self.alertContentLabel.font = [UIFont systemFontOfSize:13.0f];
    [self addSubview:self.alertContentLabel];
    //self
    CGFloat selfHeight = TitleMarginTop + self.alertTitleLabel.font.lineHeight + ContentMarginTop + contentH + BtnMarginTop + kButtonHeight;
    CGFloat selfMarginLeft = (ScreenWidth - SelfWidth) / 2;
    self.frame = CGRectMake(selfMarginLeft, (ScreenHeight - selfHeight) / 2, SelfWidth, selfHeight);
    self.clipsToBounds = YES;
    self.layer.cornerRadius = 10.0;
    self.backgroundColor = [UIColor whiteColor];
    //collectionView
    [self addSubview:self.collectionView];
    _collectionView.delegate = self;
    _collectionView.dataSource = self;
    [_collectionView registerNib:[UINib nibWithNibName:@"XBAlertBtnCell" bundle:[NSBundle mainBundle]] forCellWithReuseIdentifier:btnCellOneID];
    [_collectionView registerNib:[UINib nibWithNibName:@"XBAlertBtnCellTwo" bundle:[NSBundle mainBundle]] forCellWithReuseIdentifier:btnCellTwoID];
    //X按钮
    UIButton *xButton = [UIButton buttonWithType:UIButtonTypeCustom];
    [xButton setImage:[UIImage imageNamed:@"btn_close_normal.png"] forState:UIControlStateNormal];
    [xButton setImage:[UIImage imageNamed:@"btn_close_selected.png"] forState:UIControlStateHighlighted];
    xButton.frame = CGRectMake(self.frame.size.width - 32, 0, 32, 32);
    [self addSubview:xButton];
    [xButton addTarget:self action:@selector(dismissAlert) forControlEvents:UIControlEventTouchUpInside];
}

为了能够切合原生方式的调用，提供了-(void)addAction:(dispatch_block_t)actionBlock withTitle:(NSString*)title方法，该方法用于向XBAlertView添加按钮以及对应的响应block。

-(void)addAction:(dispatch_block_t)actionBlock withTitle:(NSString*)title{
    if(actionBlock && ![self isBlankString:title]){
        [self.blockArray addObject:actionBlock];
        [self.btnTitleArray addObject:title];
    }
}

调用后会先保存到数组当中。

在这之后，调用方调用XBAlertView的show方法进行展示。

- (void)show
{
    if(self.btnTitleArray.count == 0 || self.btnTitleArray.count > 2){
        //更新view的frame
        [self updateFrame];
    }
    [self.collectionView reloadData];
    UIViewController *topVC = [self appRootViewController];
    [topVC.view addSubview:self];
}

show方法首先会根据两个数组是否有值来决定是否更新collectionView的frame。之后调用collectionView的reloadData，数据源就是这两个数组。这样加载后collectionView就有了需要展示的按钮。

然后获取[UIApplication sharedApplication].keyWindow.rootViewController，在这个控制器的view上添加上已经布局好的XBAlertView。

但是为了营造阴影效果，在XBAlertView被添加到父view之前，会调用以下方法创建一个遮罩层。这样就能达到显示的要求。

- (void)willMoveToSuperview:(UIView *)newSuperview
{
    if (newSuperview == nil) {
        return;
    }
    UIViewController *topVC = [self appRootViewController];
    if (!self.backImageView) {
        self.backImageView = [[UIView alloc] initWithFrame:topVC.view.bounds];
        self.backImageView.backgroundColor = [UIColor blackColor];
        self.backImageView.alpha = 0.6f;
        self.backImageView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
    }
    [topVC.view addSubview:self.backImageView];
    CGRect afterFrame = CGRectMake((CGRectGetWidth(topVC.view.bounds) - self.frame.size.width) * 0.5, (CGRectGetHeight(topVC.view.bounds) - self.frame.size.height) * 0.5, self.frame.size.width, self.frame.size.height);
    self.frame = afterFrame;
    [super willMoveToSuperview:newSuperview];
}

那么接下来就是点击响应了，因为每个按钮就是collectionView的一个cell，所以按钮的点击就转为了cell的didSelectItemAtIndexPath方法。在该方法中根据索引从前面保存好的数组取出相对应的block，并调用

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
    dispatch_block_t block = self.blockArray[indexPath.row];
    block();
    [self dismissAlert];
}