plist文件写入Documents目录注意事项

一、第一种是在没有plist文件的情况下

    NSDictionary *dict1 = [NSDictionary dictionaryWithObject:@"john1" forKey:@"name1"];
    NSString *path1 = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/user1.plist"];
<span style="color:#FF0000;">// 注意这里不能使用 NSMutableDictionary *dictPlist1 = [[NSMutableDictionary alloc] initWithContentsOfFile:path1]; 
// 因为plist文件还不存在，所以初始化后dictPlist1会是空的</span>
    NSMutableDictionary *dictPlist1 = [NSMutableDictionary dictionary];
    [dictPlist1 setValuesForKeysWithDictionary:dict1];
    [dictPlist1 writeToFile:path1 atomically:YES];

二、第二种是在有plist文件的情况下，用于中途插入数据

    NSDictionary *dict2 = [NSDictionary dictionaryWithObject:@"john2" forKey:@"name2"];
    NSString *path2 = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/user2.plist"];
<span style="color:#FF0000;">// 这里使用不能使用上面那种初始化，那样会把之前的数据初始化</span>
    NSMutableDictionary *dictPlist2 = [[NSMutableDictionary alloc] initWithContentsOfFile:path2];
    [dictPlist2 setValuesForKeysWithDictionary:dict2];
    [dictPlist2 writeToFile:path2 atomically:YES];