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，同时感谢大家提出的宝贵更新意见！
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，同时谢谢大家。 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查看网上文章或者官网文档。
1.返回输入键盘
- (BOOL)textFieldShouldReturn:(UITextField *)textField {
<span style="white-space:pre"> </span>[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.自适应父视图的大小
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
- (NSInteger)tableView:(UITableView *)tableView indentationLevelForRowAtIndexPath:(NSIndexPath *)indexPath {
<span style="white-space:pre"> </span> NSInteger row = indexPath.row;
<span style="white-space:pre"> </span>return row;
}
NSString *path = [[NSBundle mainBundle] pathForResource:@"States" ofType:@"plist"];
NSArray *array = [NSArray arrayWithContentsOfFile:path];
- (CGPoint)locationInView:(UIView *)view;
- (CGPoint)previousLocationInView:(UIView *)view;
@property(nonatomic,readonly) NSTimeInterval timestamp;
@property(nonatomic,readonly) UITouchPhase phase;
@property(nonatomic,readonly) NSUInteger tapCount;
NSString *plistPath = [[NSBundle mainBundle] pathForResource:@"book" ofType:@"plist"];
NSDictionary *dictionary = [NSDictionary dictionaryWithContentsOfFile:plistPath];
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];
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];
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];
myWebView = [[UIWebView alloc]initWithFrame:self.view.bounds];
[myWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.baidu.com"]]];
NSError *error;
<span style="font-size:18px;">NSString *errorString = [NSString stringWithFormat:@"AnError Occurred; %@</span><span style="font-family:Microsoft Yahei, Hiragino Sans GB, Helvetica, Helvetica Neue, 微软雅黑, Tahoma, Arial, sans-serif;color:#14191e;"><span style="font-size: 14px;">"<html><center><font size=+5 color='red'>AnError Occurred;<br>%@</font><.center><?html>"</span></span><span style="font-size:18px;">,error]; </span>
[myWebView loadHTMLString:errorString baseURL:nil];
//页面跳转了以后，停止载入
-(void)viewWillDisappear:(BOOL)animated {
<span style="white-space:pre"> </span>if (myWebView.isLoading) {
<span style="white-space:pre"> </span>[myWebView stopLoading];
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span> myWebView.delegate = nil;
<span style="white-space:pre"> </span>[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
- (void)keyboardWasShown:(NSNotification *)notification {
<span style="white-space:pre"> </span>if (keyboardShown) {
<span style="white-space:pre"> </span>return;
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>NSDictionary *info = [notification userInfo];
<span style="white-space:pre"> </span>
<span style="white-space:pre"> </span>NSValue *aValue = [info objectForKey:UIKeyboardFrameBeginUserInfoKey];
<span style="white-space:pre"> </span>CGSize keyboardSize = [aValue CGRectValue].size;
<span style="white-space:pre"> </span>CGRect viewFrame = scrollView.frame;
<span style="white-space:pre"> </span>viewFrame.size.height = keyboardSize.height;
<span style="white-space:pre"> </span>
<span style="white-space:pre"> </span>CGRect textFieldRect = activeField.frame;
<span style="white-space:pre"> </span>[scrollView scrollRectToVisible:textFieldRect animated:YES]; keyboardShown = YES;
}
- (void)keyboardWasHidden:(NSNotification *)notification {
<span style="white-space:pre"> </span>NSDictionary *info = [notification userInfo];
<span style="white-space:pre"> </span>NSValue *aValue = [info objectForKey:UIKeyboardFrameEndUserInfoKey];
<span style="white-space:pre"> </span>CGSize keyboardSize = [aValue CGRectValue].size;
<span style="white-space:pre"> </span>
<span style="white-space:pre"> </span>CGRect viewFrame = scrollView.frame;
<span style="white-space:pre"> </span>viewFrame.size.height += keyboardSize.height;
<span style="white-space:pre"> </span>scrollView.frame = viewFrame;
<span style="white-space:pre"> </span>
<span style="white-space:pre"> </span>keyboardShown = NO;
}
18.点击键盘的next按钮，在不同的textField之间换行
- (BOOL)textFieldShouldReturn:(UITextField *)textField {
<span style="white-space:pre"> </span>if ([textField returnKeyType] != UIReturnKeyDone) {
<span style="white-space:pre"> </span> NSInteger nextTag = [textField tag] + 1;
<span style="white-space:pre"> </span> UIView *nextTextField = [self.tableView viewWithTag:nextTag];
<span style="white-space:pre"> </span>[nextTextField becomeFirstResponder];
<span style="white-space:pre"> </span>}else {
<span style="white-space:pre"> </span>[textField resignFirstResponder];
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>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"];
<span style="white-space:pre"> </span>while ([scanner isAtEnd] == NO) {
<span style="white-space:pre"> </span>NSString *buffer;
<span style="white-space:pre"> </span>if ([scanner scanCharactersFromSet:numbers intoString:&buffer]) {
<span style="white-space:pre"> </span>[strippedString appendString:buffer];
<span style="white-space:pre"> </span>}else {
<span style="white-space:pre"> </span>scanner.scanLocation = [scanner scanLocation] + 1;
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span> }
<span style="white-space:pre"> </span> 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];
<span style="white-space:pre"> </span> if ([predicate evaluateWithObject:myString]) {
<span style="white-space:pre"> </span>//implement
<span style="white-space:pre"> </span>}
24.设置UITableView的滚动条颜色
self.tableView.indicatorStyle = UIScrollViewIndicatorStyleWhite;
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 {
<span style="white-space:pre"> </span>//implement
<span style="font-family: Arial, Helvetica, sans-serif;">}</span>
<span style="font-family: Arial, Helvetica, sans-serif;"> </span>
<span style="font-family: Arial, Helvetica, sans-serif;"> - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { </span>
<span style="font-family: Arial, Helvetica, sans-serif;"><span style="white-space:pre"> </span>//implement</span>
<span style="font-family: Arial, Helvetica, sans-serif;">} </span>
<span style="font-family: Arial, Helvetica, sans-serif;"> </span>
<span style="font-family: Arial, Helvetica, sans-serif;">- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {</span>
<span style="font-family: Arial, Helvetica, sans-serif;"><span style="white-space:pre"> </span>//implement</span>
<span style="font-family: Arial, Helvetica, sans-serif;"> }</span>
<span style="font-family: Arial, Helvetica, sans-serif;"> </span>
<span style="font-family: Arial, Helvetica, sans-serif;"> - (void)connectionDidFinishLoading:(NSURLConnection *)connection {</span>
<span style="font-family: Arial, Helvetica, sans-serif;"><span style="white-space:pre"> </span>//implement</span>
<span style="font-family: Arial, Helvetica, sans-serif;"> }</span>
<span style="font-family: Arial, Helvetica, sans-serif;"> </span>
<span style="font-family: Arial, Helvetica, sans-serif;"> 3. 实现委托方法 </span>
<span style="font-family: Arial, Helvetica, sans-serif;">- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { </span>
<span style="font-family: Arial, Helvetica, sans-serif;"><span style="white-space:pre"> </span>self.receiveData.length = 0;//先清空数据</span>
<span style="font-family: Arial, Helvetica, sans-serif;"> }</span>
<span style="font-family: Arial, Helvetica, sans-serif;"> </span>
<span style="font-family: Arial, Helvetica, sans-serif;"> - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {</span>
<span style="font-family: Arial, Helvetica, sans-serif;"><span style="white-space:pre"> </span> [self.receiveData appendData:data]; </span>
<span style="font-family: Arial, Helvetica, sans-serif;">} </span>
<span style="font-family: Arial, Helvetica, sans-serif;"> </span>
<span style="font-family: Arial, Helvetica, sans-serif;">- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { </span>
<span style="font-family: Arial, Helvetica, sans-serif;"><span style="white-space:pre"> </span>//错误处理 </span>
<span style="font-family: Arial, Helvetica, sans-serif;">} </span>
<span style="font-family: Arial, Helvetica, sans-serif;"> </span>
<span style="font-family: Arial, Helvetica, sans-serif;">- (void)connectionDidFinishLoading:(NSURLConnection *)connection { </span>
<span style="font-family: Arial, Helvetica, sans-serif;"><span style="white-space:pre"> </span>[UIApplication sharedApplication].networkActivityIndicatorVisible = NO; </span>
<span style="font-family: Arial, Helvetica, sans-serif;"> </span>
<span style="font-family: Arial, Helvetica, sans-serif;"><span style="white-space:pre"> </span>NSString *returnString = [[NSString alloc]initWithData:self.receiveData encoding:NSUTF8StringEncoding];</span>
<span style="font-family: Arial, Helvetica, sans-serif;"> </span>
<span style="font-family: Arial, Helvetica, sans-serif;"><span style="white-space:pre"> </span> firstTimeDownloaded = YES;</span>
<span style="font-family: Arial, Helvetica, sans-serif;"> </span>
<span style="font-family: Arial, Helvetica, sans-serif;"> } </span>
26.隐藏状态栏
[UIApplication sharedApplication].statusBarHidden = YES;
27..m和.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
28.读取一般性文件
- (void)readFromTXT {
<span style="white-space:pre"> </span> NSString *tmp;
<span style="white-space:pre"> </span> NSArray *lines;//将文件转化为一行一行的
<span style="white-space:pre"> </span>lines = [[NSString stringWithContentsOfFile:@"testFileReadLines.txt"] componentsSeparatedByString:@"\n"];
<span style="white-space:pre"> </span>NSEnumerator *nse = [lines objectEnumerator]; //读取<>里的内容
<span style="white-space:pre"> </span>while (tmp == [nse nextObject]) {
<span style="white-space:pre"> </span>NSString *stringBetweenBrackets = nil;
<span style="white-space:pre"> </span>NSScanner *scanner = [NSScanner scannerWithString:tmp];
<span style="white-space:pre"> </span>[scanner scanUpToString:@"<" intoString:nil];
<span style="white-space:pre"> </span>[scanner scanString:@"<" intoString:nil]; <span style="white-space:pre"> </span>
<span style="white-space:pre"> </span>[scanner scanUpToString:@">" intoString:&stringBetweenBrackets];
<span style="white-space:pre"> </span>NSLog(@"%@",[stringBetweenBrackets description]);
<span style="white-space:pre"> </span>}
}
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.app
31.获取版本信息
UIDevice *myDevice = [UIDevice currentDevice];
NSString *systemVersion = myDevice.systemVersion;
32.UIWebView的使用
webView.delegate = self;
(BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
<span style="white-space:pre"> </span>NSURL *url = request.URL; NSString *urlStirng = url.absoluteString;
<span style="white-space:pre"> </span>NSLog(@"%@",urlStirng);
<span style="white-space:pre"> </span>return YES;
}
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 {
<span style="white-space:pre"> </span>MPMoviePlayerController *theMovie = [aNotification object];
<span style="white-space:pre"> </span>[[NSNotificationCenter defaultCenter] removeObserver:self name:MPMoviePlayerPlaybackDidFinishNotification object:theMovie];
}
34.延迟一段时间执行某个方法
[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设置成为圆角
mainView.layer.cornerRadius = 6; mainView.layer.masksToBounds = YES;
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;
Objective-C内存管理
1.一个对象可以有一个或多个拥有者
2.当它一个拥有者都没有的时候，它就会被回收
3.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
1.alloc 为对象分配内存，计数设为1，并返回此对象。
2.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。
3.retain 对象计数+1，并成为次对象的拥有者。
4.release 对象计数-1，并丢掉此对象。
5.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
1.一个代码块内要确保copy，alloc 和 retain 的使用数量与 release 和 autorelease 的数量相等。
2.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。
3.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）。
总结
不积跬步无以至千里，不积小流无以成江海
——— 与君共勉！