Objective-C(十八、謂語使用及執行個體說明)——iOS開發基礎

結合之前的學習筆記以及參考《Objective-C程式設計全解(第三版)》，對Objective-C知識點進行梳理總結。知識點一直在變，僅僅是作為參考，以蘋果官方文檔為準~

十八、謂語的使用及執行個體說明

首先先介紹基本經常使用的謂詞：

（1）邏輯運算符 && AND || OR 都能夠用

（2）IN包括

（3）模糊查詢

a、以……開頭 BEGINSWITH

b、以……結尾 ENDSWITH

c、包括….字元 CONTAINS

（4）用like進行模糊查詢

通配符：*表示随意個字元 ？表示單個字元

like *a  以a結尾
like a*  以a開頭
like *a* 包括a字元
like ?a* 第二個字元為a的字元串
           

執行個體說明：

建立Book類，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: andBookName:@"C Programming"];
        Book* book2 = [[Book alloc] initWithPrice: andBookName:@"C++ Programming"];
        Book* book3 = [[Book alloc] initWithPrice: andBookName:@"Java Programming"];
        Book* book4 = [[Book alloc] initWithPrice: andBookName:@"OC guiding"];
        Book* book5 = [[Book alloc] initWithPrice: andBookName:@"iOS guiding"];
        NSArray* books = [NSArray arrayWithObjects:book1,book2,book3,book4,book5, nil];

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

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

//      模糊查詢 和 用通配符查詢

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



    }
    return ;
}
           

output：

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