sh数组快速倒序
NSArray *arr = @[@"first",@"second"];
arr = arr.reverseObjectEnumerator.allObjects;
NSLog(@"%@",arr);
数组快速去重
NSArray*arr=@[@"first",@"second",@"first"];
arr=[arrvalueForKeyPath:@"@distinctUnionOfObjects.self"];
NSLog(@"%@",arr);