去除字串中的特殊字元使用以下方法

stringByReplacingOccurrencesOfString:@" " withString:@""

- (void)viewDidLoad {
    [super viewDidLoad];
    
    NSString *str = [self gainString:@"2017-04-29 01:12:30 +0000"];
    NSLog(@"str===%@", str);
}

- (NSString *)gainString:(NSString *)string
{
    NSString *result = [string stringByReplacingOccurrencesOfString:@" " withString:@""];
    result = [result stringByReplacingOccurrencesOfString:@"-" withString:@""];
    result = [result stringByReplacingOccurrencesOfString:@":" withString:@""];
    NSLog(@"result===%@", result);
    return result;
}