寫了很長一段時間的Swift,現在轉回OC,也想使用Swift里的函數式寫法,就給OC數組擴展幾個方法.

#import <Foundation/Foundation.h>
typedef id(^MapBlock)(id item);
typedef BOOL(^FilterBlock)(id item);
typedef NSComparisonResult(^SortedBlock)(id item1, id item2);
typedef void(^ForEachBlock)(NSUInteger i, id item);
typedef BOOL(^ContainsBlock)(id item);


@interface NSArray (FunctionalExtension)
@property(nonatomic, copy, readonly) NSArray* (^map)(MapBlock block);
@property(nonatomic, copy, readonly) NSArray* (^filter)(FilterBlock block);
@property(nonatomic, copy, readonly) NSArray* (^sorted)(SortedBlock block);
@property(nonatomic, copy, readonly) NSArray* (^forEach)(ForEachBlock block);
@property(nonatomic, copy, readonly) BOOL (^contains)(ContainsBlock block);

@end

@implementation NSArray (FunctionalExtension)
- (NSArray *(^)(MapBlock))map {
    return ^(MapBlock b) {
        NSMutableArray *a = [NSMutableArray arrayWithCapacity:self.count];
        for (id obj in self) {
            [a addObject:b(obj)];
        }
        return [a copy];
    };
}

- (NSArray *(^)(FilterBlock))filter {
    return ^(FilterBlock b) {
        NSMutableArray *a = [NSMutableArray arrayWithCapacity:self.count];
        for (id obj in self) {
            if (b(obj)) {
                [a addObject:obj];
            }
        }
        return [a copy];
    };
}

- (NSArray *(^)(SortedBlock))sorted {
    return ^(SortedBlock b) {
        return [self sortedArrayUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {
            return b(obj1, obj2);
        }];
    };
}

- (NSArray *(^)(ForEachBlock))forEach {
    return ^(ForEachBlock b) {
        for (NSUInteger i = 0; i < self.count; i++) {
            b(i, self[i]);
        }
        return self;
    };
}

- (BOOL(^)(ContainsBlock))contains {
    return ^(ContainsBlock b) {
        BOOL flag = NO;
        for (id obj in self) {
            if (b(obj)) {
                flag = YES;
                break;
            }
        }
        return flag;
    };
}
@end

使用:

    NSArray *numberArray = @[@1, @11, @4, @3, @22, @2];
    
    NSArray *newArray =
    numberArray.filter(^BOOL(NSNumber *item) {
        return item.integerValue < 22;
    }).sorted(^NSComparisonResult(NSNumber *item1, NSNumber *item2) {
        return item1 < item2;
    }).map(^id(NSNumber *item) {
        return [NSString stringWithFormat:@"%@", item];
    }).forEach(^(NSUInteger i, id item) {
        NSLog(@"%@", item);
    });
    
    BOOL isContain = newArray.contains(^BOOL(NSString *item) {
        if ([item isEqualToString:@"100"]) {
            return YES;
        }
        return NO;
    });
    NSLog(@"isContain => %d", isContain);