Answers:
NSArray *array1 = [NSArray arrayWithObjects:@"1", @"2", @"3", nil];
NSString *joinedString = [array1 componentsJoinedByString:@","];
componentsJoinedByString:
将通过指定的字符串连接数组中的组件,并返回数组的字符串表示形式。
NSArray *pathArray = [NSArray arrayWithObjects:@"here",
@"be", @"dragons", nil];
NSLog(@"%@",
[pathArray componentsJoinedByString:@" "]);