NSError *error;
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:Online_Case_Lists]];
NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSArray *caselistarray = [NSJSONSerialization JSONObjectWithData:response options:NSJSONReadingMutableLeaves error:&error];
NSLog(@"列表",caselistarray);
如上代码~出现了这个警告，其实只是一时疏忽导致，没有写明输出的caselistarray的类型
改一下就好了。
NSError *error;
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:Online_Case_Lists]];
NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSArray *caselistarray = [NSJSONSerialization JSONObjectWithData:response options:NSJSONReadingMutableLeaves error:&error];
NSLog(@"列表%@",caselistarray);
iOS 笔记-Data argument not used by format string的警告处理
原文：http://www.cnblogs.com/ruixin2222/p/4876566.html