iOS:狀態(tài)欄提示控件的實現原理
現在很多流行的軟件都加入了狀態(tài)欄提示的功能,比如手機qq,微信等,今天我們就一起來看看狀態(tài)欄提示控件的原理與實現。
一、狀態(tài)欄提示的實現原理
不知道大家看到狀態(tài)欄提示控件,***感覺它是怎么實現的呢?
我們知道即使平時寫的view是充滿全屏的,也始終不會顯示到 statusBar的上層的。也就是說statusBar應該是一個特殊的view,始終位于程序的topLevel,這就容易聯想到UIKit中一個特 殊的view-----UIWindow。UIWindow有一個windowLevel的屬性剛好能實現一直保持在上層的功能,于是方向就比較明確了。 我較早寫的兩篇博客UIWindowLevel詳解以及關于UIWindow的一點兒思考中對windowLevel有過詳細的介紹和驗證。
確定了使用UIWindow來實現狀態(tài)欄提示控件,好像問題就全部解決了,真的是這樣嗎?
如果你的程序僅僅支持portrait方向的話,那么最主要的功能就結束了,剩下的事情就是文本框布局和簡單動畫的實現了。但如果你的控件要支持其他三個方向的話,就還需要處理window的旋轉。
iOS中完整的旋轉流程如下: 設備檢測到方向旋轉->UIApplication收到旋轉事件->通知window設備發(fā)生了旋轉->window通知它的 rootViewController進行旋轉->viewController會調整自身view的transform。觀察發(fā)現自始至終 window本身的位置和方向是沒有發(fā)生變化的,也就是說如果自己創(chuàng)建一個window用于展示提示,我們需要自己處理該window的旋轉,根據不同的 方向調整window的位置和transform。
綜上要實現狀態(tài)欄提示控件我們需要做以下兩件事:
1、創(chuàng)建一個UIWindow,指定它的frame為statusBar的frame,并且設置該window的windowLevel級別略高于statusBar的windowLevel。
2、注冊系統的旋轉通知,監(jiān)測設備方向變化,根據當前設備的方向做出相應的調整。
整個過程中主要用到了UIWindow和transfrom的知識,這兩部分知識我前面寫的博客都有涉及,難點主要集中在自己旋轉window這一塊。
二、Window的旋轉
UIKit通過UIWindow和UIViewContoller為我們提供了一套旋轉支持的框架,在方向變化以后viewController中view的坐標系統就已經被轉到正確的方向了,我們只需要簡單的重新布局就可以了。我們現在是直接通過UIWindow實現狀態(tài)欄提示控件,因此需要自己完成對該window進行旋轉的操作。
我們知道對當前view設置的transform是針對它的父view的,window本身就是一種特殊的view。你可能會疑問window不就是***層的view,它還有父view嗎?
答案是YES,不信的話你可以打印一下 window的superView看看。window默認方向是portrait方向,向下y坐標增加,向右x坐標增加。因此Portrait方向我們只 需要向普通的view那樣布局就可以了,其它幾個方向我們就需要用到transform和設置位置來搞定了。
下面我們看一看從Portrait方向轉到landscapeRight方向的圖示:
上圖中從左到右展示了如何將初始位置(Portrait方向),旋轉到目標位置(landscapeRight方向)的過程。
1、原始window位置位于屏幕最上方(與statusBar的位置一樣)。
2、首先我們對這個window做順時針90°旋轉,變化后到達綠色繪制位置。
3、接著我們再修改window的center到屏幕最右邊并且上下居中,達到紅色虛線所示的位置。
4、***對該window的bound進行設置,使該window充滿屏幕最右邊的區(qū)域。注意這個時候由于window的transform已經轉了90°,所以設置時width代表著高度,height代表這寬度。
下面是完整的處理旋轉到四個方向的代碼:
- - (void)updateOrientation:(NSNotification*)noti
- {
- UIInterfaceOrientation newOrientation = [[noti.userInfo valueForKey:UIApplicationStatusBarOrientationUserInfoKey] integerValue];
- NSLog(@"new orientation: %d", newOrientation);
- switch (newOrientation) {
- case UIInterfaceOrientationPortrait:
- {
- self.transform = CGAffineTransformIdentity;
- self.frame = CGRectMake(0, 0, SCREEN_WIDTH, HEIGHT);
- break;
- }
- case UIInterfaceOrientationPortraitUpsideDown:
- {
- // 先轉矩陣,坐標系統落在屏幕有右下角,朝上是y,朝左是x
- self.transform = CGAffineTransformMakeRotation(M_PI);
- self.center = CGPointMake(SCREEN_WIDTH / 2, SCREEN_HEIGHT - HEIGHT / 2);
- self.bounds = CGRectMake(0, 0, SCREEN_WIDTH, HEIGHT);
- break;
- }
- case UIInterfaceOrientationLandscapeLeft:
- {
- self.transform = CGAffineTransformMakeRotation(-M_PI_2);
- // 這個時候坐標軸已經轉了90°,調整x相當于調節(jié)豎向調節(jié),y相當于橫向調節(jié)
- self.center = CGPointMake(HEIGHT / 2, [UIScreen mainScreen].bounds.size.height / 2);
- self.bounds = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.height, HEIGHT);
- break;
- }
- case UIInterfaceOrientationLandscapeRight:
- {
- // 先設置transform,在設置位置和大小
- self.transform = CGAffineTransformMakeRotation(M_PI_2);
- self.center = CGPointMake(SCREEN_WIDTH - HEIGHT / 2, SCREEN_HEIGHT / 2);
- self.bounds = CGRectMake(0, 0, SCREEN_HEIGHT, HEIGHT);
- break;
- }
- default:
- break;
- }
- }
三、狀態(tài)欄提示控件源碼
講了那么多,說好的控件呢?
下面是完整的控件代碼:
View Code SvStatusBarTipsWindow.h
- - (void)updateOrientation:(NSNotification*)noti
- {
- UIInterfaceOrientation newOrientation = [[noti.userInfo valueForKey:UIApplicationStatusBarOrientationUserInfoKey] integerValue];
- NSLog(@"new orientation: %d", newOrientation);
- switch (newOrientation) {
- case UIInterfaceOrientationPortrait:
- {
- self.transform = CGAffineTransformIdentity;
- self.frame = CGRectMake(0, 0, SCREEN_WIDTH, HEIGHT);
- break;
- }
- case UIInterfaceOrientationPortraitUpsideDown:
- {
- // 先轉矩陣,坐標系統落在屏幕有右下角,朝上是y,朝左是x
- self.transform = CGAffineTransformMakeRotation(M_PI);
- self.center = CGPointMake(SCREEN_WIDTH / 2, SCREEN_HEIGHT - HEIGHT / 2);
- self.bounds = CGRectMake(0, 0, SCREEN_WIDTH, HEIGHT);
- break;
- }
- case UIInterfaceOrientationLandscapeLeft:
- {
- self.transform = CGAffineTransformMakeRotation(-M_PI_2);
- // 這個時候坐標軸已經轉了90°,調整x相當于調節(jié)豎向調節(jié),y相當于橫向調節(jié)
- self.center = CGPointMake(HEIGHT / 2, [UIScreen mainScreen].bounds.size.height / 2);
- self.bounds = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.height, HEIGHT);
- break;
- }
- case UIInterfaceOrientationLandscapeRight:
- {
- // 先設置transform,在設置位置和大小
- self.transform = CGAffineTransformMakeRotation(M_PI_2);
- self.center = CGPointMake(SCREEN_WIDTH - HEIGHT / 2, SCREEN_HEIGHT / 2);
- self.bounds = CGRectMake(0, 0, SCREEN_HEIGHT, HEIGHT);
- break;
- }
- default:
- break;
- }
- }
- 復制代碼
- 三、狀態(tài)欄提示控件源碼
- 講了那么多,說好的控件呢?
- 下面是完整的控件代碼:
- 復制代碼
- //
- // SvStatusBarTipsWindow.h
- // SvStatusBarTips
- //
- // Created by maple on 4/21/13.
- // Copyright (c) 2013 maple. All rights reserved.
- //
- #import <UIKit/UIKit.h>
- @interface SvStatusBarTipsWindow : UIWindow
- /*
- * @brief get the singleton tips window
- */
- + (SvStatusBarTipsWindow*)shareTipsWindow;
- /*
- * @brief show tips message on statusBar
- */
- - (void)showTips:(NSString*)tips;
- /*
- * @brief show tips message on statusBar
- */
- - (void)showTips:(NSString*)tips hideAfterDelay:(NSInteger)seconds;
- /*
- * @brief show tips icon and message on statusBar
- */
- - (void)showTipsWithImage:(UIImage*)tipsIcon message:(NSString*)message;
- /*
- * @brief show tips icon and message on statusBar
- */
- - (void)showTipsWithImage:(UIImage*)tipsIcon message:(NSString*)message hideAfterDelay:(NSInteger)seconds;
- /*
- * @brief hide tips window
- */
- - (void)hideTips;
- @end
SvStatusBarTipsWindow.m
- //
- // SvStatusBarTipsWindow.m
- // SvStatusBarTips
- //
- // Created by maple on 4/21/13.
- // Copyright (c) 2013 maple. All rights reserved.
- //
- #import "SvStatusBarTipsWindow.h"
- #define SCREEN_WIDTH ([UIScreen mainScreen].bounds.size.width)
- #define SCREEN_HEIGHT ([UIScreen mainScreen].bounds.size.height)
- #define HEIGHT 20
- #define ICON_WIDTH 20
- #define TIPMESSAGE_RIGHT_MARGIN 20
- #define ICON_RIGHT_MARGIN 5
- @interface SvStatusBarTipsWindow () {
- UILabel *_tipsLbl;
- UIImageView *_tipsIcon;
- NSTimer *_hideTimer;
- }
- @property (nonatomic, copy) NSString *tipsMessage;
- @end
- @implementation SvStatusBarTipsWindow
- @synthesize tipsMessage;
- static SvStatusBarTipsWindow *tipsWindow = nil;
- + (SvStatusBarTipsWindow*)shareTipsWindow
- {
- if (!tipsWindow) {
- static dispatch_once_t onceToken;
- dispatch_once(&onceToken, ^{
- tipsWindow = [[super allocWithZone:NULL] init];
- });
- }
- return tipsWindow;
- }
- + (id)copyWithZone:(NSZone *)zone
- {
- return [[self shareTipsWindow] retain];
- }
- + (id)allocWithZone:(NSZone *)zone
- {
- return [[self shareTipsWindow] retain];
- }
- - (id)retain
- {
- return tipsWindow;
- }
- - (oneway void)release
- {
- return;
- }
- - (id)autorelease
- {
- return tipsWindow;
- }
- - (id)init
- {
- CGRect frame = [UIApplication sharedApplication].statusBarFrame;
- self = [super initWithFrame:frame];
- if (self) {
- self.autoresizingMask = UIViewAutoresizingFlexibleWidth;
- self.windowLevel = UIWindowLevelStatusBar + 10;
- self.backgroundColor = [UIColor clearColor];
- _tipsIcon = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, ICON_WIDTH, ICON_WIDTH)];
- _tipsIcon.autoresizingMask = UIViewAutoresizingFlexibleHeight;
- _tipsIcon.backgroundColor = [UIColor redColor];
- [self addSubview:_tipsIcon];
- [_tipsIcon release];
- _tipsLbl = [[UILabel alloc] initWithFrame:self.bounds];
- #ifdef NSTextAlignmentRight
- _tipsLbl.textAlignment = NSTextAlignmentLeft;
- _tipsLbl.lineBreakMode = NSLineBreakByTruncatingTail;
- #else
- _tipsLbl.textAlignment = 0; // means UITextAlignmentLeft
- _tipsLbl.lineBreakMode = 4; //UILineBreakModeTailTruncation;
- #endif
- _tipsLbl.textColor = [UIColor whiteColor];
- _tipsLbl.font = [UIFont systemFontOfSize:12];
- _tipsLbl.backgroundColor = [UIColor blackColor];
- _tipsLbl.autoresizingMask = UIViewAutoresizingFlexibleHeight;
- [self addSubview:_tipsLbl];
- [_tipsLbl release];
- [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(updateOrientation:) name:UIApplicationWillChangeStatusBarOrientationNotification object:nil];
- }
- return self;
- }
- - (void)dealloc
- {
- [[NSNotificationCenter defaultCenter] removeObserver:self];
- [tipsMessage release];
- [super dealloc];
- }
- #pragma mark -
- #pragma mark Notification Handle
- - (void)updateOrientation:(NSNotification*)noti
- {
- UIInterfaceOrientation newOrientation = [[noti.userInfo valueForKey:UIApplicationStatusBarOrientationUserInfoKey] integerValue];
- NSLog(@"new orientation: %d", newOrientation);
- switch (newOrientation) {
- case UIInterfaceOrientationPortrait:
- {
- self.transform = CGAffineTransformIdentity;
- self.frame = CGRectMake(0, 0, SCREEN_WIDTH, HEIGHT);
- break;
- }
- case UIInterfaceOrientationPortraitUpsideDown:
- {
- // 先轉矩陣,坐標系統落在屏幕有右下角,朝上是y,朝左是x
- self.transform = CGAffineTransformMakeRotation(M_PI);
- self.center = CGPointMake(SCREEN_WIDTH / 2, SCREEN_HEIGHT - HEIGHT / 2);
- self.bounds = CGRectMake(0, 0, SCREEN_WIDTH, HEIGHT);
- break;
- }
- case UIInterfaceOrientationLandscapeLeft:
- {
- self.transform = CGAffineTransformMakeRotation(-M_PI_2);
- // 這個時候坐標軸已經轉了90°,調整x相當于調節(jié)豎向調節(jié),y相當于橫向調節(jié)
- self.center = CGPointMake(HEIGHT / 2, [UIScreen mainScreen].bounds.size.height / 2);
- self.bounds = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.height, HEIGHT);
- break;
- }
- case UIInterfaceOrientationLandscapeRight:
- {
- // 先設置transform,在設置位置和大小
- self.transform = CGAffineTransformMakeRotation(M_PI_2);
- self.center = CGPointMake(SCREEN_WIDTH - HEIGHT / 2, SCREEN_HEIGHT / 2);
- self.bounds = CGRectMake(0, 0, SCREEN_HEIGHT, HEIGHT);
- break;
- }
- default:
- break;
- }
- }
- #pragma mark -
- #pragma mark Tips Method
- /*
- * @brief show tips message on statusBar
- */
- - (void)showTips:(NSString*)tips
- {
- if (_hideTimer) {
- [_hideTimer invalidate];
- [_hideTimer release];
- }
- _tipsIcon.image = nil;
- _tipsIcon.hidden = YES;
- CGSize size = [tips sizeWithFont:_tipsLbl.font constrainedToSize:CGSizeMake(320, 30)];
- size.width += TIPMESSAGE_RIGHT_MARGIN;
- if (size.width > self.bounds.size.width - ICON_WIDTH) {
- size.width = self.bounds.size.width - ICON_WIDTH;
- }
- _tipsLbl.frame = CGRectMake(self.bounds.size.width - size.width, 0, size.width, self.bounds.size.height);
- _tipsLbl.text = tips;
- [self makeKeyAndVisible];
- }
- - (void)showTips:(NSString*)tips hideAfterDelay:(NSInteger)seconds
- {
- [self showTips:tips];
- _hideTimer = [NSTimer scheduledTimerWithTimeInterval:seconds target:self selector:@selector(hideTips) userInfo:nil repeats:NO];
- }
- /*
- * @brief show tips icon and message on statusBar
- */
- - (void)showTipsWithImage:(UIImage*)tipsIconImage message:(NSString*)message
- {
- if (_hideTimer) {
- [_hideTimer invalidate];
- [_hideTimer release];
- }
- CGSize size = [message sizeWithFont:_tipsLbl.font constrainedToSize:self.bounds.size];
- size.width += TIPMESSAGE_RIGHT_MARGIN;
- if (size.width > self.bounds.size.width - ICON_WIDTH) {
- size.width = self.bounds.size.width - ICON_WIDTH;
- }
- _tipsLbl.frame = CGRectMake(self.bounds.size.width - size.width, 0, size.width, self.bounds.size.height);
- _tipsLbl.text = message;
- _tipsIcon.center = CGPointMake(self.bounds.size.width - _tipsLbl.bounds.size.width - ICON_WIDTH / 2 - ICON_RIGHT_MARGIN, self.bounds.size.height / 2);
- _tipsIcon.image = tipsIconImage;
- _tipsIcon.hidden = NO;
- [self makeKeyAndVisible];
- }
- - (void)showTipsWithImage:(UIImage*)tipsIconImage message:(NSString*)message hideAfterDelay:(NSInteger)seconds
- {
- [self showTipsWithImage:tipsIconImage message:message];
- _hideTimer = [NSTimer scheduledTimerWithTimeInterval:seconds target:self selector:@selector(hideTips) userInfo:nil repeats:NO];
- }
- /*
- * @brief hide tips window
- */
- - (void)hideTips
- {
- self.hidden = YES;
- }
- @end
該狀態(tài)欄提示控件實現了添加提示圖標和提示文字,以及自動隱藏等功能。顯示和隱藏動畫實 現起來比較簡單,控件中就沒有實現,大家可以根據需要隨意發(fā)揮。該控件使用單例模式,接口非常簡單,使用起來很方便。上面代碼相信大家都能看得懂,這里就不展開講了,有什么問題歡迎討論。