一步一步熟悉Mac app开发（五）之Menu Bar和Popover

#概要
本文共分为个阶段，每个阶段完成后都可以看到阶段性成果。
阶段一、显示Menu Bar小图标。
阶段二、隐藏程序窗口和启动栏图标。（无图）
阶段三、点击MenuBar小图标，出现菜单。
阶段四、点击MenuBar小图标，出现一个小窗口。
阶段五、通过事件监听鼠标点击，“智能”关闭小窗口。

#阶段一
1.创建工程，向工程中加入图标，对图标资源进行设置。

2.在AppDelegate.h中添加NSStatusItem类型的指针变量，对其进行初始化操作，定义一个getDiamond函数。

//AppDelegate.m
#import "AppDelegate.h"

@interface AppDelegate ()

@property NSStatusItem *statusItem;
- (void) getDiamond:(NSStatusBarButton *)sender;

@end

@implementation AppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    // Insert code here to initialize your application
    
    //初始化_statusItem
    _statusItem = [[NSStatusBar systemStatusBar] statusItemWithLength:NSVariableStatusItemLength];
    
    //设置_statusItem按钮相关信息
    NSStatusBarButton *button = _statusItem.button;
    if(button){
        button.image = [NSImage imageNamed:@"zuan"];
        button.action = @selector(getDiamond:);
    }
}

- (void) getDiamond:(NSStatusBarButton *)sender {
    NSLog(@"You get a lot of diamonds!");
}

- (void)applicationWillTerminate:(NSNotification *)aNotification {
    // Insert code here to tear down your application
}
@end

3.Command+R运行，效果如下。

#阶段二
1.打开storyboard，选中窗口，取消勾选【Is initial Controller】便可去掉窗口。

2.打开工程设置，点击【Info】，新增“Application is agent (UIElement)”选项，其值为YES。

3.阶段二完成！

#阶段三

1.注释掉AppDelegate.m中applicationDidFinishLaunching函数内部的如下语句

//button.action = @selector(getDiamond:);

2.在applicationDidFinishLaunching函数中添加如下语句。

    NSMenu *menu;
    menu = [[NSMenu alloc] init];
    [menu addItem:[[NSMenuItem alloc] initWithTitle:@"Get Diamond" action:@selector(getDiamond:) keyEquivalent:@"g"] ];
    [menu addItem:[NSMenuItem separatorItem]];
    [menu addItem:[[NSMenuItem alloc] initWithTitle:@"Quit" action:@selector(terminate:) keyEquivalent:@"q"] ];
    _statusItem.menu = menu;

3.AppDelegate.m修改后的完整版代码如下。

#import "AppDelegate.h"
@interface AppDelegate ()
@property NSStatusItem *statusItem;
- (void) getDiamond:(NSStatusBarButton *)sender;
@end

@implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    // Insert code here to initialize your application
    
    //初始化_statusItem
    _statusItem = [[NSStatusBar systemStatusBar] statusItemWithLength:NSVariableStatusItemLength];
    
    //设置_statusItem按钮相关信息
    NSStatusBarButton *button = _statusItem.button;
    if(button){
        button.image = [NSImage imageNamed:@"zuan"];
        //button.action = @selector(getDiamond:);
    }
    
    NSMenu *menu;
    menu = [[NSMenu alloc] init];
    [menu addItem:[[NSMenuItem alloc] initWithTitle:@"Get Diamond" action:@selector(getDiamond:) keyEquivalent:@"g"] ];
    [menu addItem:[NSMenuItem separatorItem]];
    [menu addItem:[[NSMenuItem alloc] initWithTitle:@"Quit" action:@selector(terminate:) keyEquivalent:@"q"] ];
    _statusItem.menu = menu;
}

- (void) getDiamond:(NSStatusBarButton *)sender {
    NSLog(@"You get a lot of diamonds!");
}

- (void)applicationWillTerminate:(NSNotification *)aNotification {
    // Insert code here to tear down your application
}
@end

4.阶段三完成，效果如下。

#阶段四

1.添加一个ViewController的子类GetDiamonds，创建xib文件，声明并完成其初始化方法。

//DiamondViewController.h
#import <Cocoa/Cocoa.h>
@interface DiamondViewController : NSViewController
- (id) initWithCustom;
@end

//DiamondViewController.m
- (id) initWithCustom{
    self = [super initWithNibName:@"DiamondViewController" bundle:nil];
    return self;
}

2.点击DiamondViewController.xib文件，选择label拖拽直View中央。

3.打开AppDelegate.m，新增一个NSPopver的指针变量，新增部分代码，完成后代码如下。

#import "AppDelegate.h"
#import "DiamondViewController.h"
@interface AppDelegate ()

@property NSStatusItem *statusItem;
@property NSPopover *popover;
- (void) getDiamond:(NSStatusBarButton *)sender;
- (void)toggleWeather:(NSStatusBarButton *)sender
@end

@implementation AppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    // Insert code here to initialize your application
    
    //初始化_statusItem
    _statusItem = [[NSStatusBar systemStatusBar] statusItemWithLength:NSVariableStatusItemLength];
    
    //设置_statusItem按钮相关信息
    NSStatusBarButton *button = _statusItem.button;
    if(button){
        button.image = [NSImage imageNamed:@"zuan"];
        //修改
        button.action = @selector(toggleDiamond:);
    }
// 将menu注释掉。
//    NSMenu *menu;
//    menu = [[NSMenu alloc] init];
//    [menu addItem:[[NSMenuItem alloc] initWithTitle:@"Get Diamond" action:@selector(getDiamond:) keyEquivalent:@"g"] ];
//    [menu addItem:[NSMenuItem separatorItem]];
//    [menu addItem:[[NSMenuItem alloc] initWithTitle:@"Quit" action:@selector(terminate:) keyEquivalent:@"q"] ];
//    _statusItem.menu = menu;
  
    //新增
    _popover = [[NSPopover alloc] init];
    _popover.contentViewController = [[DiamondViewController alloc] initWithCustom];
}

- (void) getDiamond:(NSStatusBarButton *)sender {
    NSLog(@"You get a lot of diamonds!");
}

//新增
- (void)toggleDiamond:(NSStatusBarButton *)sender{
    if([_popover isShown]){
        [_popover performClose:sender];
    }else{
        NSStatusBarButton *button = _statusItem.button;
        if(button){
            [_popover showRelativeToRect:button.bounds ofView:button preferredEdge:NSRectEdgeMinY];
        }
    }
}

- (void)applicationWillTerminate:(NSNotification *)aNotification {
    // Insert code here to tear down your application
}
@end

4.阶段四完成，效果如下。

#阶段五
1.新建NSObject的子类EventMonitor，代码如下。

//EventMonitor.h
import <Cocoa/Cocoa.h>
@interface EventMonitor : NSObject
@property id monitor;
@property NSEventMask mask;
@property void (^handler)(NSEvent *);
- (id) initWithMaskAndHandler:(NSEventMask)mask handler:(void (^)(NSEvent *))handler;
- (void) start;
- (void) stop;
@end

//EventMonitor.m
#import "EventMonitor.h"
@implementation EventMonitor
- (id) initWithMaskAndHandler:(NSEventMask)mask handler:(void (^)(NSEvent *)) handler {
    self = [super init];
    if(self){
        _mask = mask;
        _handler = handler;
    }
    return self;
}

- (void) start{
    _monitor = [NSEvent addGlobalMonitorForEventsMatchingMask:_mask handler:_handler];
}

- (void) stop{
    if(_monitor != nil ){
        [NSEvent removeMonitor:_monitor];
        _monitor = nil;
    }
}
@end

3.打开AppDelegate.m，添加EventMonitor的成员变量，并对其进行初始化。

@property EventMonitor* eventMonitor;
 _eventMonitor = [[EventMonitor alloc] initWithMaskAndHandler:NSEventMaskLeftMouseUp|NSEventMaskRightMouseUp handler:^(NSEvent *h) {
        if([_popover isShown]){
            [self closePopover:h];
        }
    }];

4.对代码进行修改，新增closePopover和showPopover函数，修改toggleDiamond函数部分代码。

//新增
-(void) closePopover:(id)sender{
    [_popover performClose:sender];
    
    [_eventMonitor stop];
}

//新增
-(void) showPopover:(id)sender{
    NSStatusBarButton *button = [_statusItem button];
    if(button){
        [_popover showRelativeToRect:button.bounds ofView:button preferredEdge:NSRectEdgeMinY];
    }
    [_eventMonitor start];
}

-(void) toggleDiamond:(NSStatusBarButton *)sender{
    if([_popover isShown]){
        //修改
        [self closePopover:sender];
    }else{
        //修改
        [self showPopover:sender];
    }
}

5.阶段五完成，效果如下。

#结语
想了解更多关于Popover的用法，详见：一步一步熟悉Mac app开发（九）之NSPopover