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使用Objective-C块

coding-style objective-c

Sean · 技术社区 · 16 年前

@interface NSArray (FunWithBlocks)
- (NSArray *)collect:(id (^)(id obj))block;
- (NSArray *)select:(BOOL (^)(id obj))block;
- (NSArray *)flattenedArray;
@end

NSArray *packagePaths = [[[NSSearchPathForDirectoriesInDomains(NSAllApplicationsDirectory, NSAllDomainsMask, YES) collect:^(id path) { return (id)[[[NSFileManager defaultManager] contentsOfDirectoryAtPath:path error:nil] collect:^(id file) { return (id)[path stringByAppendingPathComponent:file]; }]; }] flattenedArray] select:^(id fullPath) { return [[NSWorkspace sharedWorkspace] isFilePackageAtPath:fullPath]; }];

NSMutableArray *packagePaths = [NSMutableArray new];
for (NSString *searchPath in NSSearchPathForDirectoriesInDomains(NSAllApplicationsDirectory, NSAllDomainsMask, YES)) {
    for (NSString *file in [[NSFileManager defaultManager] contentsOfDirectoryAtPath:searchPath error:nil]) {
        NSString *packagePath = [searchPath stringByAppendingPathComponent:file];
        if ([[NSWorkspace sharedWorkspace] isFilePackageAtPath:packagePath]) {
            [packagePaths addObject:packagePath];
        }
    }
}

3 回复 | 直到 11 年前

bbum 16 年前

使用换行符,将通话拆分为多条线路。

你已经做到了。很好。

现在,当编写使用所述API的代码时,请执行以下操作:

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSAllApplicationsDirectory, NSAllDomainsMask, YES);
paths = [paths collect: ^(id path) {
    ...
}];
paths = [paths collect: ^(id path) {
    ...
}];
paths = [paths select: ^(id path) {
    ...
}];

即,将收集/选择/过滤/展平/映射/任何步骤作为单独的步骤进行。这不会比链式方法调用更快/更慢。

如果您确实需要在块的侧面嵌套块,那么请使用完整缩进:

paths = [paths collect: ^(id path) {
    ...
    [someArray select:^(id path) {
        ...
    }];
}];

就像嵌套if语句等。当它变得太复杂时,根据需要将其重构为函数或方法。

Rayfleck 12 年前

NSArray *packagePaths = [[[NSSearchPathForDirectoriesInDomains(NSAllApplicationsDirectory, NSAllDomainsMask, YES) 
                            collect:^(id path) {
                                      return [[[NSFileManager defaultManager] 
                                                 contentsOfDirectoryAtPath:path 
                                                                     error:nil] 
                                               collect:^(id file) { 
                                                         return [path stringByAppendingPathComponent:file]; 
                                                        }
                                             ]; 
                                     }
                            ] 
                            flattenedArray
                          ] 

                          select:^(id fullPath) { 
                                   return [[NSWorkspace sharedWorkspace] isFilePackageAtPath:fullPath]; 
                                 }
                         ];

NSResponder 16 年前

看起来你正在重新发明高阶消息。Marcel Weiher在Objective-C中的HOM方面做了大量的工作,你可以在这里找到:

http://www.metaobject.com/blog/labels/Higher%20Order%20Messaging.html