Objective-C(十八、谓语使用及实例说明)——iOS开发基础

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结合之前的学习笔记以及參考《Objective-C编程全解(第三版)》，对Objective-C知识点进行梳理总结。知识点一直在变，仅仅是作为參考，以苹果官方文档为准~

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十八、谓语的使用及实例说明

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首先先介绍基本经常使用的谓词：

（1）逻辑运算符 && AND || OR 都能够用

（2）IN包括

（3）模糊查询

a、以……开头 BEGINSWITH

b、以……结尾 ENDSWITH

c、包括….字符 CONTAINS

（4）用like进行模糊查询

通配符：*表示随意个字符 ？表示单个字符

like *a  以a结尾
like a*  以a开头
like *a* 包括a字符
like ?a* 第二个字符为a的字符串

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实例说明：

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创建Book类，Book.h

@interface Book : NSObject
{
    NSInteger _price;
    NSString* _bookName;
}

- (instancetype)initWithPrice:(NSInteger)price andBookName:(NSString *)bookName;

@end

Book.h

#import "Book.h"

@implementation Book

- (instancetype)initWithPrice:(NSInteger)price andBookName:(NSString *)bookName {
    if (self = [super init]) {
        _price = price;
        _bookName = bookName;
    }
    return self;
}

- (NSString *)description {

    return [NSString stringWithFormat:@"Book price:%li,named %@",_price,_bookName];
}

@end

main.m

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Book* book1 = [[Book alloc] initWithPrice:20 andBookName:@"C Programming"];
        Book* book2 = [[Book alloc] initWithPrice:32 andBookName:@"C++ Programming"];
        Book* book3 = [[Book alloc] initWithPrice:18 andBookName:@"Java Programming"];
        Book* book4 = [[Book alloc] initWithPrice:45 andBookName:@"OC guiding"];
        Book* book5 = [[Book alloc] initWithPrice:28 andBookName:@"iOS guiding"];
        NSArray* books = [NSArray arrayWithObjects:book1,book2,book3,book4,book5, nil];

        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"price > %i",30];
        NSArray *filterArray = [books filteredArrayUsingPredicate:predicate];
        NSLog(@"%@",filterArray);

//      逻辑运算符 和 IN
        predicate = [NSPredicate predicateWithFormat:@"bookName IN {'C Programming','C++ Programming'} AND price > 30"];
        filterArray = [books filteredArrayUsingPredicate:predicate];
        NSLog(@"%@",filterArray);

//      模糊查询 和 用通配符查询

        predicate = [NSPredicate predicateWithFormat:@"bookName CONTAINS 'guiding' || bookName like '*Program*' "]; //包括guiding或者包括Program
        filterArray = [books filteredArrayUsingPredicate:predicate];
        NSLog(@"%@",filterArray);

    }
    return 0;
}

output：

2015-07-09 20:17:24.403 exercise_谓语[632:9877] (
    "Book price:32,named C++ Programming",
    "Book price:45,named OC guiding"
)
2015-07-09 20:17:24.404 exercise_谓语[632:9877] (
    "Book price:32,named C++ Programming"
)
2015-07-09 20:17:24.407 exercise_谓语[632:9877] (
    "Book price:20,named C Programming",
    "Book price:32,named C++ Programming",
    "Book price:18,named Java Programming",
    "Book price:45,named OC guiding",
    "Book price:28,named iOS guiding"
)