参考链接：
NSPredicate
Cocoa提供了一个NSPredicate类,它用来指定过滤器的条件
初始化方法
+ (NSPredicate *)predicateWithFormat:(NSString *)predicateFormat, ...;
Format：
/* * 1.格式说明符 %d和%@等插入数值和字符串,%K表示key 还可以引入变量名,用$,类似环境变量,如:@"name == $NAME",再用predicateWithSubstitutionVariables调用来构造新的谓词(键/值字典),其中键是变量名,值是要插入的内容,注意这种情况下不能把变量当成键路径,只能用作值 2.运算符 ==等于 >:大于 >=和=>:大于或等于 <:小于 <=和=<:小于或等于 !=和<>:不等于 括号和逻辑运算AND、OR、NOT或者C样式的等效表达式&&、||、! 注意：不等号适用于数字和字符串 3. 数组运算符 BETWEEN和IN后加某个数组，可以用{50,200}，也可以用%@格式说明符插入自己的对象，也可以用变量 4.SELF足够了 self就表示对象本身 5.字符串运算符 BEGINSWITH:以某个字符串开头 ENDSWITH:以某个字符串结束 CONTAINS:包含某个字符串 @"name ENDSWITH[d] 'ang'" [c],[d],[cd],后缀表示不区分大小写，不区分发音符号，两这个都不区分 6.LIKE运算符 类似SQL的LIKES LIKE，与通配符“*”表示任意多和“?”表示一个结合使用 LIKE也接受[cd]符号 7.MATCHES可以使用正则表达式 NSString *regex = @"^A.+e$"; //以A开头，e结尾 */
数组的类目：用来过滤数组
- (NSArray *)filteredArrayUsingPredicate:(NSPredicate *)predicate;
可变数组可以直接过滤
- ( void)filterUsingPredicate:(NSPredicate *)predicate;
例：过滤出数组中的字符串中含有ang的元素
NSArray *array = [[NSArray alloc]initWithObjects: @" beijing ", @" shanghai ", @" guangzou ", @" wuhan ", nil]; NSString * string = @" ang "; NSPredicate *pred = [NSPredicate predicateWithFormat: @" SELF CONTAINS %@ ", string]; NSLog( @" %@ ",[array filteredArrayUsingPredicate:pred]);
单个对象的过滤
- (BOOL)evaluateWithObject:( id) object;
例：判断字符串中首字母是不是字母
NSString *regex = @" [A-Za-z]+ "; NSPredicate *predicate = [NSPredicate predicateWithFormat: @" SELF MATCHES %@ ", regex]; if ([predicate evaluateWithObject: @" hahaa "]) { NSLog( @" 首字母含有字母 "); } else { NSLog( @" 首字母不含字母 "); }
过滤语句：邮箱过滤@"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{1,5}";
电话号码部分：@"^1(3[0-9]|5[0-35-9]|8[025-9])\\d{8}$"
NSRegularExpression
字符串替换
NSError* error = NULL; NSRegularExpression* regex = [NSRegularExpression regularExpressionWithPattern: @" (encoding=\ ")[^\ " ]+(\") " options: 0 error:&error]; NSString* sample = @" <xml encoding=\ "abc\ " ></xml><xml encoding=\"def\"></xml><xml encoding=\"ttt\"></xml> "; NSLog( @" Start:%@ ",sample); NSString* result = [regex stringByReplacingMatchesInString:sample options: 0 range:NSMakeRange( 0, sample.length) withTemplate: @" $1utf-8$2 "]; NSLog( @" Result:%@ ", result);
字符串中截取字符串
// 组装一个字符串，需要把里面的网址解析出来 NSString *urlString= @" <meta/><link/><title>1Q84 BOOK1</title></head><body> "; // NSRegularExpression类里面调用表达的方法需要传递一个NSError的参数。下面定义一个 NSError *error; // http+:[^\\s]* 这个表达式是检测一个网址的。(?<=title\>).*(?=</title)截取html文章中的<title></title>中内文字的正则表达式 NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern: @" (?<=title\\>).*(?=</title) " options: 0 error:&error]; if (regex != nil) { NSTextCheckingResult *firstMatch=[regex firstMatchInString:urlString options: 0 range:NSMakeRange( 0, [urlString length])]; if (firstMatch) { NSRange resultRange = [firstMatch rangeAtIndex: 0]; // 从urlString当中截取数据 NSString *result=[urlString substringWithRange:resultRange]; // 输出结果 NSLog( @" ->%@<- ",result); } }
NSPredicate测试：
其中自定义一个类，出事的时候给属性赋值，用runtime获取所有属性并重写description方法
@interface DataModel : NSObject @property (nonatomic,copy)NSString *name; @property (nonatomic,assign)NSInteger num; @end
#import " DataModel.h " #import <objc/runtime.h> @implementation DataModel - (instancetype)init { self = [super init]; if (self) { self.name = @" haha "; self.num = 12; } return self; } // 修改描述文件（获取所有属性存成字典） - (NSString *)description { u_int count; objc_property_t* properties= class_copyPropertyList([self class], &count); NSMutableDictionary *dic = [[NSMutableDictionary alloc]init]; for ( int i = 0; i < count ; i++) { const char* propertyName = property_getName(properties[i]); NSString *strName = [NSString stringWithCString:propertyName encoding:NSUTF8StringEncoding]; [dic setObject:[self valueForKey:strName] forKey:strName]; } return [NSString stringWithFormat: @" <%@ %p>:%@ ",self. class,&self,dic]; }
例子：
// (1)比较运算符>,<,==,>=,<=,!= - ( void)test1 { DataModel *model = [[DataModel alloc]init]; // 类里面 /* self.name = @"haha"; self.num = 12; */ // 可判定一个类的一个属性是否等于某个值,字符串是否相等 NSPredicate *predicate = [NSPredicate predicateWithFormat: @" num > 11 "]; BOOL match = [predicate evaluateWithObject:model]; NSLog( @" %@ ",match? @" yes ": @" no "); } // 强悍的数组过滤功能 - ( void)test2 { NSMutableArray *mutableArray = [[NSMutableArray alloc]init]; DataModel *model1= [[DataModel alloc]init]; DataModel *model2 = [[DataModel alloc]init]; DataModel *model3 = [[DataModel alloc]init]; model2.num = 8; model3.name = @" lala "; [mutableArray addObject:model1]; [mutableArray addObject:model2]; [mutableArray addObject:model3]; NSPredicate *predicate = [NSPredicate predicateWithFormat: @" num > 10 AND name == 'lala' "]; [mutableArray filterUsingPredicate:predicate]; NSLog( @" 过滤出了: %@ ",mutableArray); } // 含有变量的谓词,在这里用><会崩溃 - ( void)test3 { DataModel *model= [[DataModel alloc]init]; NSPredicate *predicate = [NSPredicate predicateWithFormat: @" name == $key "]; NSDictionary *dic = @{ @" key ": @" haha "}; NSPredicate *predicate1 = [predicate predicateWithSubstitutionVariables:dic]; NSLog( @" %@ ",predicate1); BOOL match = [predicate1 evaluateWithObject:model]; NSLog( @" %@ ",match? @" yes ": @" no "); } // BETWEEN // BETWEEN和IN后加某个数组，可以用{50,200}，也可以用%@格式说明符插入自己的对象，也可以用变量 - ( void)test4 { NSMutableArray *mutableArray = [[NSMutableArray alloc]init]; DataModel *model1= [[DataModel alloc]init]; DataModel *model2 = [[DataModel alloc]init]; DataModel *model3 = [[DataModel alloc]init]; model2.num = 8; model3.num = 20; [mutableArray addObject:model1]; [mutableArray addObject:model2]; [mutableArray addObject:model3]; NSPredicate *predicate = [NSPredicate predicateWithFormat: @" num BETWEEN {5,15} "]; [mutableArray filterUsingPredicate:predicate]; NSLog( @" 过滤出了: %@ ",mutableArray); } // IN运算符 - ( void)test5 { NSArray *arrayFilter = [NSArray arrayWithObjects: @" abc1 ", @" abc2 ", nil]; NSMutableArray *arrayContent = [NSMutableArray arrayWithObjects: @" a1 ", @" abc1 ", @" abc4 ", @" abc2 ", nil]; // 过滤出arrayContent 不包含 arrayFilter的元素 NSPredicate *thePredicate = [NSPredicate predicateWithFormat: @" NOT (SELF in %@) ", arrayFilter]; [arrayContent filterUsingPredicate:thePredicate]; NSLog( @" %@ ",arrayContent); } // BEGINSWITH,ENDSWITH,CONTAINS // LIKE运算符（通配符） - ( void)test6 { NSMutableArray *mutableArray = [[NSMutableArray alloc]init]; DataModel *model1= [[DataModel alloc]init]; DataModel *model2= [[DataModel alloc]init]; DataModel *model3= [[DataModel alloc]init]; model1.name = @" a123.png "; model3.name = @" a.png "; [mutableArray addObject:model1]; [mutableArray addObject:model2]; [mutableArray addObject:model3]; NSPredicate *predicate = [NSPredicate predicateWithFormat: @" name LIKE[cd] 'a*.png' "]; [mutableArray filterUsingPredicate:predicate]; NSLog ( @" %@ ", mutableArray); }