字符串操作range注意事项

代码：

{
    NSString *string = @"";
    NSString *ret = [string stringByReplacingCharactersInRange:NSMakeRange(0, 0) withString:@"因吹斯汀"];
    NSLog(@"string:%@\nret:%@", string, ret); //因吹斯汀
}
{
    NSString *string = @"倒计时开关是";
    NSString *ret = [string stringByReplacingCharactersInRange:NSMakeRange(0, 0) withString:@"因吹斯汀"];
    NSLog(@"string:%@\nret:%@", string, ret); //因吹斯汀倒计时开关是
}
{
    NSString *string = @"倒计时开关是";
    NSString *ret = [string stringByReplacingCharactersInRange:NSMakeRange(0, 1) withString:@"因吹斯汀"];
    NSLog(@"string:%@\nret:%@", string, ret); //因吹斯汀计时开关是
}
{
    NSString *string = @"倒计时开关是";
    NSString *ret = [string stringByReplacingCharactersInRange:NSMakeRange(string.length, 0) withString:@"因吹斯汀"]; //倒计时开关是因吹斯汀
    NSLog(@"string:%@\nret:%@", string, ret);
}
{
    NSString *string = @"倒计时开关是";
    NSString *ret = [string stringByReplacingCharactersInRange:NSMakeRange(string.length - 1, 1) withString:@"因吹斯汀"]; //倒计时开关因吹斯汀
    NSLog(@"string:%@\nret:%@", string, ret);
}
{
    NSString *string = @"倒计时开关是";
    NSString *ret = [string stringByReplacingCharactersInRange:NSMakeRange(string.length, 1) withString:@"因吹斯汀"]; //崩溃
    NSLog(@"string:%@\nret:%@", string, ret);
}

总结：

传入的range必须满足：(range.location + range.length) <= string.length，否则会发生越界崩溃。