使用格式大致如下：
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-相关命令"
//需要操作的代码
#pragma clang diagnostic pop
栗子1：忽略弃用的警告⚠️
UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"" message:@"" delegate:nil cancelButtonTitle:@"" otherButtonTitles:@"", nil];
[alertView show];
//方法弃用告警
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
UIAlertView *alertViewTmp = [[UIAlertView alloc]initWithTitle:@"" message:@"" delegate:nil cancelButtonTitle:@"" otherButtonTitles:@"", nil];
[alertViewTmp show];
#pragma clang diagnostic pop
栗子2：忽略不兼容指针类型⚠️
// 不兼容指针类型
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wincompatible-pointer-types"
//
#pragma clang diagnostic pop
栗子3：循环引用⚠️
break the retain cycle.
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-retain-cycles"
// self.completionBlock = ^ {
// ...
// };
#pragma clang diagnostic pop
栗子4：未使用变量 ⚠️
// 未使用变量
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused-variable"
int a;
#pragma clang diagnostic pop
栗子5：未使用default ⚠️
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wcovered-switch-default"
// switch (style) {
// case UITableViewCellStyleDefault:
// case UITableViewCellStyleValue1:
// case UITableViewCellStyleValue2:
// case UITableViewCellStyleSubtitle:
// // ...
// default:
// return;
// }
#pragma clang diagnostic pop
http://blog.csdn.net/zww1984774346/article/details/53409033
