转载：iOS开发过程中的各种tips
前言
iOS开发过程中，总有那么一些个小问题让人纠结，它们不会让程序崩溃，但是会让人崩溃。除此之外，还将分享一些细节现在我通过自己的总结以及从其他地方的引用，来总结一下一些常见小问题。
本篇长期更新，多积累，多奉献，同时感谢其中一些文章的作者的整理，感谢！
iOS高级开发实战讲解这是我在网上搜索到的iOS高级开发实战讲解，由于原文不是很方便浏览，所以我在这里整理一部分出来，方便查阅，同时谢谢原作者。
这里我不是每一个都收录进来，这里只是放出一部分，有些用的太多，我就没整理了，大家如果想看可以去看原文。
1.返回输入键盘
<UITextFieldDelegate> - (BOOL)textFieldShouldReturn:(UITextField *)textField { [textField resignFirstResponder]; return YES; }2.CGRect
CGRectFromString(<#NSString *string#>)//有字符串恢复出矩形 CGRectInset(<#CGRect rect#>, <#CGFloat dx#>, <#CGFloat dy#>)//创建较小或者较大的矩形 CGRectIntersectsRect(<#CGRect rect1#>, <#CGRect rect2#>)//判断两巨星是否交叉，是否重叠 CGRectZero//高度和宽度为零的，位于（0，0）的矩形常量3.隐藏状态栏
[UIApplication sharedApplication] setStatusBarHidden:<#(BOOL)#> withAnimation:<#(UIStatusBarAnimation)#>//隐藏状态栏4.自动适应父视图大小
self.view.autoresizesSubviews = YES; self.view.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;5.UITableView的一些方法
这里我自己做了个测试，缩进级别设置为行号，row越大，缩进越多 <UITableViewDelegate> - (NSInteger)tableView:(UITableView *)tableView indentationLevelForRowAtIndexPath:(NSIndexPath *)indexPath { NSInteger row = indexPath.row; return row; }6.把plist文件中的数据赋给数组
NSString *path = [[NSBundle mainBundle] pathForResource:@"States" ofType:@"plist"]; NSArray *array = [NSArray arrayWithContentsOfFile:path];7.获取触摸的点
- (CGPoint)locationInView:(UIView *)view; - (CGPoint)previousLocationInView:(UIView *)view;8.获取触摸的属性
@property(nonatomic,readonly) NSTimeInterval timestamp; @property(nonatomic,readonly) UITouchPhase phase; @property(nonatomic,readonly) NSUInteger tapCount;9.从plist中获取数据赋给字典
NSString *plistPath = [[NSBundle mainBundle] pathForResource:@"book" ofType:@"plist"]; NSDictionary *dictionary = [NSDictionary dictionaryWithContentsOfFile:plistPath];10.NSUserDefaults注意事项
设置完了以后如果存储的东西比较重要的话，一定要同步一下 [[NSUserDefaults standardUserDefaults] synchronize];11.获取Documents目录
NSString *documentsDirectory = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];12.获取tmp目录
NSString *tmpPath = NSTemporaryDirectory();13.利用Safari打开一个链接
NSURL *url = [NSURL URLWithString:@"http://baidu.com"]; [[UIApplication sharedApplication] openURL:url];14.利用UIWebView显示pdf文件，网页等等
<UIWebViewDelegate> UIWebView *webView = [[UIWebView alloc]initWithFrame:self.view.bounds]; webView.delegate = self; webView.scalesPageToFit = YES; webView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight; [webView setAllowsInlineMediaPlayback:YES]; [self.view addSubview:webView]; NSString *pdfPath = [[NSBundle mainBundle] pathForResource:@"book" ofType:@"pdf"]; NSURL *url = [NSURL fileURLWithPath:pdfPath]; NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:(NSURLRequestUseProtocolCachePolicy) timeoutInterval:5];15.UIWebView和html的简单交互
myWebView = [[UIWebView alloc]initWithFrame:self.view.bounds]; [myWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.baidu.com"]]]; NSError *error; NSString *errorString = [NSString stringWithFormat:@"<html><center><font size=+5 color='red'>AnError Occurred;<br>%@</font></center></html>",error]; [myWebView loadHTMLString:errorString baseURL:nil]; //页面跳转了以后，停止载入 -(void)viewWillDisappear:(BOOL)animated { if (myWebView.isLoading) { [myWebView stopLoading]; } myWebView.delegate = nil; [UIApplication sharedApplication].networkActivityIndicatorVisible = NO; }16.汉字转码
NSString *oriString = @"\u67aa\u738b"; NSString *escapedString = [oriString stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];17.处理键盘通知
先注册通知，然后实现具体当键盘弹出来要做什么，键盘收起来要做什么 - (void)registerForKeyboardNotifications { keyboardShown = NO;//标记当前键盘是没有显示的 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasShown:) name:UIKeyboardWillShowNotification object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasHidden:) name:UIKeyboardDidHideNotification object:nil]; } //键盘显示要做什么 - (void)keyboardWasShown:(NSNotification *)notification { if (keyboardShown) { return; } NSDictionary *info = [notification userInfo]; NSValue *aValue = [info objectForKey:UIKeyboardFrameBeginUserInfoKey]; CGSize keyboardSize = [aValue CGRectValue].size; CGRect viewFrame = scrollView.frame; viewFrame.size.height = keyboardSize.height; CGRect textFieldRect = activeField.frame; [scrollView scrollRectToVisible:textFieldRect animated:YES]; keyboardShown = YES; } - (void)keyboardWasHidden:(NSNotification *)notification { NSDictionary *info = [notification userInfo]; NSValue *aValue = [info objectForKey:UIKeyboardFrameEndUserInfoKey]; CGSize keyboardSize = [aValue CGRectValue].size; CGRect viewFrame = scrollView.frame; viewFrame.size.height += keyboardSize.height; scrollView.frame = viewFrame; keyboardShown = NO; }18.点击键盘的next按钮，在不同的textField之间换行
- (BOOL)textFieldShouldReturn:(UITextField *)textField { if ([textField returnKeyType] != UIReturnKeyDone) { NSInteger nextTag = [textField tag] + 1; UIView *nextTextField = [self.tableView viewWithTag:nextTag]; [nextTextField becomeFirstResponder]; }else { [textField resignFirstResponder]; } return YES; }19.设置日期格式
dateFormatter = [[NSDateFormatter alloc]init]; dateFormatter.locale = [NSLocale currentLocale]; dateFormatter.calendar = [NSCalendar autoupdatingCurrentCalendar]; dateFormatter.timeZone = [NSTimeZone defaultTimeZone]; dateFormatter.dateStyle = NSDateFormatterShortStyle; NSLog(@"%@",[dateFormatter stringFromDate:[NSDate date]]);20.加载大量图片的时候，可以使用
NSString *imagePath = [[NSBundle mainBundle] pathForResource:@"icon" ofType:@"png"]; UIImage *myImage = [UIImage imageWithContentsOfFile:imagePath];21.有时候在iPhone游戏中，既要播放背景音乐，同时又要播放比如枪的开火音效。
NSString *musicFilePath = [[NSBundle mainBundle] pathForResource:@"xx" ofType:@"wav"]; NSURL *musicURL = [NSURL fileURLWithPath:musicFilePath]; AVAudioPlayer *musicPlayer = [[AVAudioPlayer alloc]initWithContentsOfURL:musicURL error:nil]; [musicPlayer prepareToPlay]; musicPlayer.volume = 1; musicPlayer.numberOfLoops = -1;//-1表示一直循环22.从通讯录中读取电话号码，去掉数字之间的-
NSString *originalString = @"(123)123123abc"; NSMutableString *strippedString = [NSMutableString stringWithCapacity:originalString.length]; NSScanner *scanner = [NSScanner scannerWithString:originalString]; NSCharacterSet *numbers = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"]; while ([scanner isAtEnd] == NO) { NSString *buffer; if ([scanner scanCharactersFromSet:numbers intoString:&buffer]) { [strippedString appendString:buffer]; }else { scanner.scanLocation = [scanner scanLocation] + 1; } } NSLog(@"%@",strippedString);23.正则判断：字符串只包含字母和数字
NSString *myString = @"Letter1234"; NSString *regex = @"[a-z][A-Z][0-9]"; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",regex]; if ([predicate evaluateWithObject:myString]) { //implement }24.设置UITableView的滚动条颜色
self.tableView.indicatorStyle = UIScrollViewIndicatorStyleWhite;网络编程 开发web等网络应用程序的时候，需要确认网络环境，连接情况等信息。如果没有处理它们，是不会通过apple的审查的。 系统自带的网络检查是原生的，AFNetworking也为我们添加了相关检测机制，所以这个直接在介绍AFNetworking的时候详解吧。
25.使用NSURLConnection下载数据
1. 创建对象 NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://www.baidu.com"]]; [NSURLConnection connectionWithRequest:request delegate:self]; 2. NSURLConnection delegate 委托方法 - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { } - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { } - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { } 3. 实现委托方法 - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { self.receiveData.length = 0;//先清空数据 } - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { [self.receiveData appendData:data]; } - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { //错误处理 } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { [UIApplication sharedApplication].networkActivityIndicatorVisible = NO; NSString *returnString = [[NSString alloc]initWithData:self.receiveData encoding:NSUTF8StringEncoding]; firstTimeDownloaded = YES; }iOS的动画以及自定义图形，开个专栏总结。
26.隐藏状态栏
[UIApplication sharedApplication].statusBarHidden = YES; 27..m文件与.mm文件的区别
.m文件是objective-c文件 .mm文件相当于c++或者c文件Safari其实没有把内存的缓存写到存储卡上
28.读取一般性文件
- (void)readFromTXT { NSString *tmp; NSArray *lines;//将文件转化为一行一行的 lines = [[NSString stringWithContentsOfFile:@"testFileReadLines.txt"] componentsSeparatedByString:@"\n"]; NSEnumerator *nse = [lines objectEnumerator]; //读取<>里的内容 while (tmp == [nse nextObject]) { NSString *stringBetweenBrackets = nil; NSScanner *scanner = [NSScanner scannerWithString:tmp]; [scanner scanUpToString:@"<" intoString:nil]; [scanner scanString:@"<" intoString:nil]; [scanner scanUpToString:@">" intoString:&stringBetweenBrackets]; NSLog(@"%@",[stringBetweenBrackets description]); } }29.隐藏UINavigationBar
[self.navigationController setNavigationBarHidden:YES animated:YES];30.调用电话，短信，邮件
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"mailto:[email protected]?Subject=hello"]]; sms://调用短信 tel://调用电话 itms://打开MobileStore.app31.获取版本信息
UIDevice *myDevice = [UIDevice currentDevice]; NSString *systemVersion = myDevice.systemVersion; 32.UIWebView的使用
<UIWebViewDelegate> webView.delegate = self; (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType { NSURL *url = request.URL; NSString *urlStirng = url.absoluteString; NSLog(@"%@",urlStirng); return YES; } UIButton的title和image不能同时显示 UINavigationItem也是
33.NSNotificationCenter带参数发送
MPMoviePlayerController *theMovie = [[MPMoviePlayerController alloc]initWithContentURL:[NSURL fileURLWithPath:moviePath]]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(myMovieFinishedCallback:) name:MPMoviePlayerPlaybackDidFinishNotification object:theMovie]; [theMovie play]; - (void)myMovieFinishedCallback:(NSNotification *)aNotification { MPMoviePlayerController *theMovie = [aNotification object]; [[NSNotificationCenter defaultCenter] removeObserver:self name:MPMoviePlayerPlaybackDidFinishNotification object:theMovie]; }34.延迟一段时间执行某个函数
[self performSelector:@selector(dismissModal) withObject:self afterDelay:1.0]; 35.用NSDateFormatter调整时间格式代码
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init]; dateFormatter.dateFormat = @"yyyy-MM-dd HH:mm:ss"; NSString *currentDateStr = [dateFormatter stringFromDate:[NSDate date]]; 36.UIView设置成圆角的方法
mainView.layer.cornerRadius = 6; mainView.layer.masksToBounds = YES;- 一个对象可以有一个或多个拥有者
- 当它一个拥有者都没有的时候，它就会被回收
- 如果想保留一个对象不被回收，你就必须成为它的拥有者
关键字
- alloc 为对象分配内存，计数设为1，并返回此对象。
- copy 复制一个对象，此对象计数为1，返回此对象。你将成为此克隆对象的拥有者。
- retain 对象计数+1，并成为次对象的拥有者。
- release 对象计数-1，并丢掉此对象。
- autorelease 在未来的某一个时刻，对象计数-1。并在未来的某个时间放弃此对象。
原则
- 一个代码块内要确保copy，alloc 和 retain 的使用数量与 release 和 autorelease 的数量相等。
- 在使用以 alloc 或 new 开头或包含 copy 的方法，或 retain 一个对象时，你将会编程它的拥有者。
- 实现 dealloc 方法，这是系统当 retain -> 0 的时候，自动调用的。手动调用会引起 retain count 计数错误（多一次的 release）。
iPhone 更改键盘右下角按键的 type
SearchBar *mySearchBar = [[UISearchBar alloc]init]; mySearchBar.frame = CGRectMake(0, 0, self.view.bounds.size.width, 44); mySearchBar.placeholder = @"placeholderString"; mySearchBar.delegate = self; [self.view addSubview:mySearchBar]; UITextField *searchField = [[mySearchBar subviews] lastObject]; searchField.returnKeyType = UIReturnKeyDone;