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copied!<p>My block-based solution might look a bit overkill, but if you have several of this requirements, it could be helpful:</p> <p>create a Category on NSArray:</p> <pre><code>@interface NSArray (FunctionalTools) - (NSArray *)arrayByPerformingBlock:(id (^)(id element))performBlock; @end @implementation NSArray (FunctionalTools) - (NSArray *)arrayByPerformingBlock:(id (^)(id element))performBlock { NSMutableArray *array = [NSMutableArray array]; for (id element in self){ [array addObject:performBlock(element)]; } return array; } @end </code></pre> <p>and use it like this:</p> <pre><code>#import "NSArray+FunctionalTools.h" //.... self.youtubeVideos = [NSArray arrayWithObjects: @"http://example.com/index.php?number=1&keyword=", @"http://example.com/index.php?number=2&keyword=", nil]; self.youtubeVideos = [youtubeVideos arrayByPerformingBlock:^id(id element) { return [element stringByAppendingString:@"KeyWord"];}]; NSLog(@"%@", youtubeVideos); </code></pre> <p>or even </p> <pre><code>self.youtubeVideos = [[NSArray arrayWithObjects: @"http://example.com/index.php?number=1&keyword=", @"http://example.com/index.php?number=2&keyword=", nil] arrayByPerformingBlock:^id(id element) { return [element stringByAppendingString:@"KeyWord"];}]; </code></pre> <p><strong>Edit</strong><br> I incorporated this example into a <a href="https://github.com/vikingosegundo/arraytools" rel="nofollow">sample project</a> I wrote to teach myself block-based techniques to use functional-style programming with Objective-C. Coming from Python I always missed List Comprehension like </p> <pre><code>l = ['aa', 'ab','c','ad','dd'] l = [i+i for i in l if i.startswith('a')] </code></pre> <p>Block-based it looks like this:</p> <pre><code>NSArray *array = [NSArray arrayWithObjects:@"aa", @"ab",@"c",@"ad",@"dd", nil]; array = [array arrayByPerformingBlock:^id(id element) { return [element stringByAppendingString:element]; } ifElementPassesTest:^BOOL(id element) {return [element hasPrefix:@"a"];}]; </code></pre>

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