UIPopoverPresentationController简

1.相关属性

1. sourceRect：指定箭头所指区域的矩形框范围，以sourceview的左上角为坐标原点
2. permittedArrowDirections：箭头方向
3. sourceView：sourceRect以这个view的左上角为原点
4. barButtonItem：若有navigationController,并且从right/leftBarButtonItem点击后出现popover,则可以把right/leftBarButtonItem看做上面说的sourceView.默认箭头指向up，亲测下来up是最合适的方向，所以在这种情况下可以不设置箭头方向。

UIPopoverPresentationController是UIViewController的一个属性，所以并不需要你特地去建立
一个UIPopoverPresentationController来进行操作，而应该建立一个UIViewController。

2. 效果图

系统的.png

3. 代码实现

1. ViewController中的实现：

#import "ViewController.h"
#import "PopoverViewController.h"

@interface ViewController ()<UIPopoverPresentationControllerDelegate>

@property (strong, nonatomic) UIButton *button;
@property (strong, nonatomic) PopoverViewController *buttonPopVC;
@property (strong, nonatomic) PopoverViewController *itemPopVC;
@property (strong, nonatomic) NSString *currentPop;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"item" style:UIBarButtonItemStylePlain target:self action:@selector(rightItemClick)];

    self.view.backgroundColor = [UIColor whiteColor];
    _button = [[UIButton alloc] initWithFrame:CGRectMake(20, 100, 100, 40)];
    [_button setTitle:@"button" forState:UIControlStateNormal];
    [_button setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
    [self.view addSubview:_button];
    [_button addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(tableDidSelected:) name:@"click" object:nil];
}

- (void)rightItemClick{
    self.itemPopVC = [[PopoverViewController alloc] init];
    self.itemPopVC.modalPresentationStyle = UIModalPresentationPopover;
    self.itemPopVC.popoverPresentationController.barButtonItem = self.navigationItem.rightBarButtonItem;  //rect参数是以view的左上角为坐标原点（0，0）
    self.itemPopVC.popoverPresentationController.permittedArrowDirections = UIPopoverArrowDirectionUnknown; //箭头方向,如果是baritem不设置方向，会默认up，up的效果也是最理想的
    self.itemPopVC.popoverPresentationController.delegate = self;
    [self presentViewController:self.itemPopVC animated:YES completion:nil];

}

//处理popover上的talbe的cell点击
- (void)tableDidSelected:(NSNotification *)notification {
    NSIndexPath *indexpath = (NSIndexPath *)notification.object;
    switch (indexpath.row) {
        case 0:
            self.view.backgroundColor = [UIColor greenColor];
            break;
        case 1:
            self.view.backgroundColor = [UIColor grayColor];
            break;
        case 2:
            self.view.backgroundColor = [UIColor blueColor];
            break;
        case 3:
            self.view.backgroundColor = [UIColor purpleColor];
            break;
        case 4:
            self.view.backgroundColor = [UIColor yellowColor];
            break;
    }
    if (self.buttonPopVC) {
        [self.buttonPopVC dismissViewControllerAnimated:YES completion:nil];    //我暂时使用这个方法让popover消失，但我觉得应该有更好的方法，因为这个方法并不会调用popover消失的时候会执行的回调。
        self.buttonPopVC = nil;

    }else{
        [self.itemPopVC dismissViewControllerAnimated:YES completion:nil];
        self.itemPopVC = nil;
    }
}

- (void)buttonClick:(UIButton *)sender{
    self.buttonPopVC = [[PopoverViewController alloc] init];
    self.buttonPopVC.modalPresentationStyle = UIModalPresentationPopover;
    self.buttonPopVC.popoverPresentationController.sourceView = _button;  //rect参数是以view的左上角为坐标原点（0，0）
    self.buttonPopVC.popoverPresentationController.sourceRect = _button.bounds; //指定箭头所指区域的矩形框范围（位置和尺寸），以view的左上角为坐标原点
    self.buttonPopVC.popoverPresentationController.permittedArrowDirections = UIPopoverArrowDirectionUp; //箭头方向
    self.buttonPopVC.popoverPresentationController.delegate = self;
    [self presentViewController:self.buttonPopVC animated:YES completion:nil];
}

- (UIModalPresentationStyle)adaptivePresentationStyleForPresentationController:(UIPresentationController *)controller{
    return UIModalPresentationNone;
}

- (BOOL)popoverPresentationControllerShouldDismissPopover:(UIPopoverPresentationController *)popoverPresentationController{
    return NO;   //点击蒙版popover不消失， 默认yes
}

@end

2. 自定义类

@interface PopoverViewController : UIViewController<UITableViewDataSource, UITableViewDelegate>
@property (strong, nonatomic) UITableView *tableView;
@property (strong, nonatomic) NSMutableArray *colorArray;

@end

#import "PopoverViewController.h"

@implementation PopoverViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.tableView = [[UITableView alloc] initWithFrame:self.view.frame];
    [self.view addSubview:self.tableView];
    self.tableView.dataSource = self;
    self.tableView.delegate = self;
    self.tableView.scrollEnabled = NO;

    self.colorArray = [[NSMutableArray alloc] initWithObjects:@"green",@"gray", @"blue",@"purple", @"yellow", nil];
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
    return self.colorArray.count;
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
    return 1;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
    static NSString *identifer = @"cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifer];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifer];
    }
    cell.textLabel.text = [NSString stringWithFormat:@"%@", self.colorArray[indexPath.row]];
    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
    [[NSNotificationCenter defaultCenter] postNotificationName:@"click" object:indexPath];
}

//重写preferredContentSize，让popover返回你期望的大小
- (CGSize)preferredContentSize {
    if (self.presentingViewController && self.tableView != nil) {
        CGSize tempSize = self.presentingViewController.view.bounds.size;
        tempSize.width = 150;
        CGSize size = [self.tableView sizeThatFits:tempSize];  //sizeThatFits返回的是最合适的尺寸，但不会改变控件的大小
        return size;
    }else {
        return [super preferredContentSize];
    }
}

- (void)setPreferredContentSize:(CGSize)preferredContentSize{
    super.preferredContentSize = preferredContentSize;
}
@end