NSArray * array1=[self.dic1 allKeys];
NSMutableString * str2=(NSMutableString *)[array1 componentsJoinedByString:@","];
NSLog(@"方法二拼接的字符串是%@",str2);
数组元素转字符串iOS
原文：http://my.oschina.net/u/2329800/blog/512764
