搜索
在一个字符串中搜索子字符串
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最灵活的方法
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- (NSRange)rangeOfString:(NSString *)aString options:(NSStringCompareOptions)mask range:(NSRange)searchRange locale:(NSLocale *)locale |
格式化字符串
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3个方法
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-initWithFormat: -initWithFormat:arguments: +stringWithFormat: |
整数
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可以同时工作在32位和64位的
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uint64_t p = 2305843009213693951; NSString *s = [NSString stringWithFormat:@ "The ninth Mersenne prime is %llu" , (unsigned long long) p]; // "The ninth Mersenne prime is 2305843009213693951" |
Modifier | d, i | o, u, x, X |
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hh | signed char | unsigned char |
h | short | unsigned short |
(none) | int | unsigned int |
l(ell) | long | unsigned long |
j | intmax_t | uintmax_t |
t | ptrdiff_t | |
z | size_t |
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转换规则
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int m = -150004021; uint n = 150004021U; NSString *s = [NSString stringWithFormat:@ "d:%d i:%i o:%o u:%u x:%x X:%X" , m, m, n, n, n, n]; // "d:-150004021 i:-150004021 o:1074160465 u:150004021 x:8f0e135 X:8F0E135" //o是八进制 |
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设置最小字段宽度和最小数字位数
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int m = 42; NSString *s = [NSString stringWithFormat:@ "'%4d' '%-4d' '%+4d' '%4.3d' '%04d'" , m, m, m, m, m]; // "[ 42] [42 ] [ +42] [ 042] [0042]" m = -42; NSString *s = [NSString stringWithFormat:@ "'%4d' '%-4d' '%+4d' '%4.3d' '%04d'" , m, m, m, m, m]; // "[ -42] [-42 ] [ -42] [-042] [-042]" |
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%p可打印指针,和%#x不同的是它可以同时在32位和64位执行
浮点数
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使用%f和%g
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double v[5] = {12345, 12, 0.12, 0.12345678901234, 0.0000012345678901234}; NSString *s = [NSString stringWithFormat:@ "%g %g %g %g %g" , v[0], v[1], v[2], v[3], v[4]]; // "12345 12 0.12 0.123457 1.23457e-06" NSString *s = [NSString stringWithFormat:@ "%f %f %f %f %f" , v[0], v[1], v[2], v[3], v[4]]; // "12345.000000 12.000000 0.120000 0.123457 0.000001" |
多行文字
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使用 来
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NSString *limerick = @ "A lively young damsel named Menzies " @ "Inquired: «Do you know what this thenzies?» " @ "Her aunt, with a gasp, " @ "Replied: " It 's a wasp, " @"And you' re holding the end where the stenzies. "; |
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等价写法
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NSString *limerick = @ "A lively young damsel named Menzies Inquired: «Do you know what this thenzies?» Her aunt, with a gasp, Replied: " It 's a wasp, And you' re holding the end where the stenzies. "; |
更简洁的方法
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NSString * string = @ "The man " @ "who knows everything " @ "learns nothing" @ "." ; |
替换字符串
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NSMutableString的四个方法
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-deleteCharactersInRange: -insertString:atIndex: -replaceCharactersInRange:withString: -replaceOccurrencesOfString:withString:options:range: |
NSString的方法
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-stringByReplacingOccurrencesOfString:withString: -stringByReplacingOccurrencesOfString:withString:options:range: -stringByReplacingCharactersInRange:withString: |
NSMutableString不会创建新字符串,性能会好点
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NSMutableString *string; // 假设我们已经有了一个名为 string 的字符串 // 现在要去掉它的一个前缀,做法如下: NSString *prefix = @ "WeDon’tWantThisPrefix" NSRange r = [string rangeOfString:prefix options:NSAnchoredSearch range:NSMakeRange(0, string.length) locale:nil]; if (r.location != NSNotFound) { [string deleteCharactersInRange:r]; } |
连接字符串
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NSArray *names = @[ "Hildr" , @ "Heidrun" , @ "Gerd" , @ "Guðrún" , @ "Freya" , @ "Nanna" , @ "Siv" , @ "Skaði" , @ "Gróa" ]; NSString *result = [names componentsJoinedByString:@ ", " ]; |
字符串解析
正则表达式
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NSError *error = nil; NSString *pattern = @ "(w+) = #(p{Hex_Digit}{6})" ; NSRegularExpression *expression = [NSRegularExpression regularExpressionWithPattern:pattern options:0 error:&error]; NSTextCheckingResult *result = [expression firstMatchInString:string options:0 range:NSMakeRange(0, string.length)]; NSString *key = [string substringWithRange:[result rangeAtIndex:1]]; NSString *value = [string substringWithRange:[result rangeAtIndex:2]]; |
将字符串分解成数组,使用componentsSeparatedByString:这个方法,或者 enumerateSubstringsInRange:options:usingBlock:。如果是按照行来进行分解可以使用option这个参数 传NSStringEnumerationByLines
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NSString *input = @“ backgroundColor = #ff0000 textColor = #0000ff " NSString *pattern = @" (w+) = #([da-f]{6})"; NSRegularExpression *expression = [NSRegularExpression regularExpressionWithPattern:pattern options:0 error:NULL]; NSArray *lines = [input componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]]; NSMutableDictionary *result = [NSMutableDictionary dictionary]; for (NSString *line in lines) { NSTextCheckingResult *textCheckingResult = [expression firstMatchInString:line options:0 range:NSMakeRange(0, line.length)]; NSString* key = [line substringWithRange:[textCheckingResult rangeAtIndex:1]]; NSString* value = [line substringWithRange:[textCheckingResult rangeAtIndex:2]]; result[key] = value; } return result; |
扫描
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NSScanner
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NSScanner *scanner = [NSScanner scannerWithString:string]; //默认情况下,扫描器会跳过所有空格符和换行符。但这里我们只希望跳过空格符 scanner.charactersToBeSkipped = [NSCharacterSet whitespaceCharacterSet]; //定义一个十六进制字符集 NSCharacterSet *hexadecimalCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@ "0123456789abcdefABCDEF" ]; NSMutableDictionary *result = [NSMutableDictionary dictionary]; while (!scanner.isAtEnd) { NSString *key = nil; NSString *value = nil; NSCharacterSet *letters = [NSCharacterSet letterCharacterSet]; BOOL didScan = [scanner scanCharactersFromSet:letters intoString:&key] && [scanner scanString:@ "=" intoString:NULL] && [scanner scanString:@ "#" intoString:NULL] && [scanner scanCharactersFromSet:hexadecimalCharacterSet intoString:&value] && value.length == 6; result[key] = value; [scanner scanCharactersFromSet:[NSCharacterSet newlineCharacterSet] intoString:NULL]; // 继续扫描下一行 } return result; |
解析器
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设计一个能够用(100,0,255)或者#ff0000这样的字符来定义颜色的方法。
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- (NSDictionary *)parse:(NSString *)string error:(NSError **)error { self.scanner = [NSScanner scannerWithString:string]; self.scanner.charactersToBeSkipped = [NSCharacterSet whitespaceCharacterSet]; NSMutableDictionary *result = [NSMutableDictionary dictionary]; NSCharacterSet *letters = [NSCharacterSet letterCharacterSet] while (!self.scanner.isAtEnd) { NSString *key = nil; UIColor *value = nil; BOOL didScan = [self.scanner scanCharactersFromSet:letters intoString:&key] && [self.scanner scanString:@ "=" intoString:NULL] && [self scanColor:&value]; result[key] = value; [self.scanner scanCharactersFromSet:[NSCharacterSet newlineCharacterSet] intoString:NULL]; // 继续扫描下一行 } } - (BOOL)scanColor:(UIColor **)out { return [self scanHexColorIntoColor:out] || [self scanTupleColorIntoColor:out]; } //扫描设置#ff0000这样的 - (BOOL)scanHexColorIntoColor:(UIColor **)out { NSCharacterSet *hexadecimalCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@ "0123456789abcdefABCDEF" ]; NSString *colorString = NULL; if ([self.scanner scanString:@ "#" intoString:NULL] && [self.scanner scanCharactersFromSet:hexadecimalCharacterSet intoString:&colorString] && colorString.length == 6) { *out = [UIColor colorWithHexString:colorString]; return YES; } return NO; } - (BOOL)scanTupleColorIntoColor:(UIColor **)out { NSInteger red, green, blue = 0; BOOL didScan = [self.scanner scanString:@ "(" intoString:NULL] && [self.scanner scanInteger:&red] && [self.scanner scanString:@ "," intoString:NULL] && [self.scanner scanInteger:&green] && [self.scanner scanString:@ "," intoString:NULL] && [self.scanner scanInteger:&blue] && [self.scanner scanString:@ ")" intoString:NULL]; if (didScan) { *out = [UIColor colorWithRed:(CGFloat)red/255. green:(CGFloat)green/255. blue:(CGFloat)blue/255. alpha:1]; return YES; } else { return NO; } } |
符号化处理
先进星扫描,使用NSScanner来解析这个表达式
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myView.left = otherView.right * 2 + 10 viewController.view.centerX + myConstant <= self.view.centerX |
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NSScanner *scanner = [NSScanner scannerWithString:contents]; NSMutableArray *tokens = [NSMutableArray array]; while (![scanner isAtEnd]) { for (NSString *operator in @[@ "=" , @ "+" , @ "*" , @ ">=" , @ "<=" , @ "." ]) { if ([scanner scanString:operator intoString:NULL]) { [tokens addObject:operator]; } } } //接下来识别非符号的只包含字母的string NSString *result = nil; if ([scanner scanCharactersFromSet:[NSCharacterSet letterCharacterSet] intoString:&result]) { [tokens addObject:result]; } //NSScanner有scanDouble:来扫描double double doubleResult = 0; if ([scanner scanDouble:&doubleResult]) { [tokens addObject:@(doubleResult)]; } //完成后用将需要解析的表达式放入试试 NSString* example = @ "myConstant = 100 " @ " myView.left = otherView.right * 2 + 10 " @ "viewController.view.centerX + myConstant <= self.view.centerX" ; NSArray *result = [self.scanner tokenize:example]; NSArray *expected = @[@ "myConstant" , @ "=" , @100, @ "myView" , @ "." , @ "left" , @ "=" , @ "otherView" , @ "." , @ "right" , @ "*" , @2, @ "+" , @10, @ "viewController" , @ "." , @ "view" , @ "." , @ "centerX" , @ "+" , @ "myConstant" , @ "<=" , @ "self" , @ "." , @ "view" , @ "." , @ "centerX" ]; XCTAssertEqualObjects(result, expected); |
进行语法解析,需要语法分析库描述我们的语言。下面代码就是为那个布局约束语言写的解析语法,用的扩展的巴科斯范式EBNF写法:
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constraint = expression comparator expression comparator = "=" | ">=" | "<=" expression = keyPath "." attribute addMultiplier addConstant keyPath = identifier | identifier "." keyPath attribute = "left" | "right" | "top" | "bottom" | "leading" | "trailing" | "width" | "height" | "centerX" | "centerY" | "baseline" addMultiplier = "*" atom addConstant = "+" atom atom = number | identifier |
还有很多Objective-C的语法解析,更多的可以在CocoaPods上找到:http://cocoapods.org/?q=parse。比较好的就是CoreParse,地址:https://github.com/beelsebob/CoreParse,但是需要使用它支持的语法。下面就是CoreParse支持的格式:
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NSString* grammarString = [@[ @ "Atom ::= num@'Number' | ident@'Identifier';" , @ "Constant ::= name@'Identifier' '=' value@<Atom>;" , @ "Relation ::= '=' | '>=' | '<=';" , @ "Attribute ::= 'left' | 'right' | 'top' | 'bottom' | 'leading' | 'trailing' | 'width' | 'height' | 'centerX' | 'centerY' | 'baseline';" , @ "Multiplier ::= '*' num@'Number';" , @ "AddConstant ::= '+' num@'Number';" , @ "KeypathAndAttribute ::= 'Identifier' '.' <AttributeOrRest>;" , @ "AttributeOrRest ::= att@<Attribute> | 'Identifier' '.' <AttributeOrRest>;" , @ "Expression ::= <KeypathAndAttribute> <Multiplier>? <AddConstant>?;" , @ "LayoutConstraint ::= lhs@<Expression> rel@<Relation> rhs@<Expression>;" , @ "Rule ::= <Atom> | <LayoutConstraint>;" , ] componentsJoinedByString:@ " " ]; |
一个规则匹配后解析器就找到同样名称的类
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- (id)parser:(CPParser *)parser didProduceSyntaxTree:(CPSyntaxTree *)syntaxTree NSString *ruleName = syntaxTree.rule.name; if ([ruleName isEqualToString:@ "Attribute" ]) { return self.layoutAttributes[[[syntaxTree childAtIndex:0] keyword]]; } ... } |
完整的解析器代码在:https://github.com/objcio/issue-9-string-parsing。里面有个解析类可以用来解析复杂的布局约束,如下:
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viewController.view.centerX + 20 <= self.view.centerX * 0.5 |
可以得到如下结果,方便转换成NSLayoutConstraint对象
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(<Expression: self.keyPath=(viewController, view), self.attribute=9, self.multiplier=1, self.constant=20> -1 <Expression: self.keyPath=(self, view), self.attribute=9, self.multiplier=0.5, self.constant=0>) |
字符串的渲染
UILabel
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label默认显示一行,如果设置numberOfLines为大于1的话可以显示指定行数,如果设置为0,则多少行都显示
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attributedText属性可以显示富文本
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label的font,textColor,textAlignment,shadowColor和shadowOffset属性可以改变外观。
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改变程序内所有Label的风格,可以使用[UILabel appearance]方法
UITextField
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text field只限于单行
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UITextfield实现了UITextInputTraits协议,这个协议需要指定键盘外观和操作等细节。比如显示什么键盘和返回按键响应等
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可以通过设置左右辅助视图,或者设置背景来自定义输入框风格了。
UITextView
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相比较UITextField,它能够处理多行文本
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可以使用定制Text Kit,官方文档:https://developer.apple.com/Library/ios/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/CustomTextProcessing/CustomTextProcessing.html
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可以为layout manager,text container或text storage自定义行为或替换自定义子类。
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在iOS7之前是基于WebKit的功能少,之后会有很多不同具体可以参考这两篇文章:Peter的http://petersteinberger.com/blog/2014/fixing-uitextview-on-ios-7/,Brent的http://inessential.com/2014/01/07/uitextview_the_solution
TableView中显示动态文本
Table view的Delegate有个方法用来计算高度:tableView:heightForRowAtIndexPath:。自定义一个UITableViewCell的子类
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- (void)layoutSubviews { [ super layoutSubviews]; self.textLabel.frame = CGRectInset(self.bounds, MyTableViewCellInset, MyTableViewCellInset); } |
计算真实高度需要使用boundingRectWithSize:options:context: 这个方法
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- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath { CGFloat labelWidth = self.tableView.bounds.size.width - MyTableViewCellInset*2; NSAttributedString *text = [self attributedBodyTextAtIndexPath:indexPath]; NSStringDrawingOptions options = NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading; CGRect boundingRect = [text boundingRectWithSize:CGSizeMake(labelWidth, CGFLOAT_MAX) options:options context:nil]; return (CGFloat) (ceil(boundingRect.size.height) + MyTableViewCellInset*2); } |
使用Text Kit和NSAttributedString进行布局
先设置attributes
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CGFloat const fontSize = 15; NSMutableDictionary *body1stAttributes = [NSMutableDictionary dictionary]; body1stAttributes[NSFontAttributeName] = [UIFont fontWithName:@ "BodoniSvtyTwoITCTT-Book" size:fontSize]; NSMutableParagraphStyle *body1stParagraph = [[NSParagraphStyle defaultParagraphStyle] mutableCopy]; body1stParagraph.alignment = NSTextAlignmentJustified; body1stParagraph.minimumLineHeight = fontSize + 3; body1stParagraph.maximumLineHeight = body1stParagraph.minimumLineHeight; body1stParagraph.hyphenationFactor = 0.97; body1stAttributes[NSParagraphStyleAttributeName] = body1stParag raph; |
这里字体为BodoniSvtyTwoITCTT,如果需要查看更多字体可以使用 +[UIFont familyNames]这个方法。为了得到字体的名字,可以使用 +[UIFont fontNamesForFamilyName:]。接下来创建段落的属性
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NSMutableDictionary *bodyAttributes = [body1stAttributes mutableCopy]; NSMutableParagraphStyle *bodyParagraph = [bodyAttributes[NSParagraphStyleAttributeName] mutableCopy]; bodyParagraph.firstLineHeadIndent = fontSize; bodyAttributes[NSParagraphStyleAttributeName] = bodyParagraph; |
装饰段落风格,使用装饰字体将文本居中对齐,装饰字符的前后加上空白段落
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NSMutableDictionary *ornamentAttributes = [NSMutableDictionary dictionary]; ornamentAttributes[NSFontAttributeName] = [UIFont fontWithName:@ "BodoniOrnamentsITCTT" size:36]; NSMutableParagraphStyle *ornamentParagraph = [[NSParagraphStyle defaultParagraphStyle] mutableCopy]; ornamentParagraph.alignment = NSTextAlignmentCenter; ornamentParagraph.paragraphSpacingBefore = fontSize; ornamentParagraph.paragraphSpacing = fontSize; ornamentAttributes[NSParagraphStyleAttributeName] = ornamentParagraph; |
显示数字表格table,表格布局示例
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NSCharacterSet *decimalTerminator = [NSCharacterSet characterSetWithCharactersInString:decimalFormatter.decimalSeparator]; NSTextTab *decimalTab = [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentCenter location:100 options:@{NSTabColumnTerminatorsAttributeName:decimalTerminator}]; NSTextTab *percentTab = [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentRight location:200 options:nil]; NSMutableParagraphStyle *tableParagraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy]; tableParagraphStyle.tabStops = @[decimalTab, percentTab]; |
显示列表的属性设置如下
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NSMutableDictionary *listAttributes = [bodyAttributes mutableCopy]; NSMutableParagraphStyle *listParagraph = [listAttributes[NSParagraphStyleAttributeName] mutableCopy]; listParagraph.headIndent = fontSize * 3; listParagraph.firstLineHeadIndent = fontSize; NSTextTab *listTab = [[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentNatural location:fontSize * 3 options:nil]; listParagraph.tabStops = @[listTab]; listAttributes[NSParagraphStyleAttributeName] = listParagraph; |
字符串本地化
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使用NSLocalizedString,可查看文章《字符串本地化》:(中文)http://objccn.io/issue-9-3/ (英文)http://www.objc.io/issue-9/string-localization.html