1。數據源是NSData類型的，也可以是NSString類型的，但是NSString類型的可以轉換為NSData類型的.
NSString *responseString;
NSData *da= [responseString dataUsingEncoding:NSUTF8StringEncoding];
NSError *error = nil;
id jsonObject = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&error];
if ([jsonObject isKindOfClass:[NSDictionary class]]){
NSDictionary *dictionary = (NSDictionary *)data;
NSLog(@"Dersialized JSON Dictionary = %@", deserializedDictionary);
}else if ([jsonObject isKindOfClass:[NSArray class]]){
NSArray *nsArray = (NSArray *)jsonObject;
NSLog(@"Dersialized JSON Array = %@", deserializedArray);
} else {
NSLog(@"An error happened while deserializing the JSON data.");
}
2，讀取項目下的文件代碼。
NSString *mainBundleDirectory=[[NSBundle mainBundle] bundlePath];
NSString *path=[mainBundleDirectory stringByAppendingPathComponent:@"123.txt"];
NSURL *url=[NSURL fileURLWithPath:path];
NSData *data = [[NSDataalloc] initWithContentsOfURL:url];
NSString* aStr=[[NSStringalloc] initWithData:data encoding:NSUTF8StringEncoding];