ios几种数据格式转换

1. NSString转换成NSData

NSString* str = @"teststring";
NSData* data = [str dataUsingEncoding:NSUTF8StringEncoding];

2. NSData转换成NSString

NSString *aString = [[NSString alloc] initWithData:adataencoding:NSUTF8StringEncoding];

3. JSON格式的NSString转换成NSMutableDictionary

NSError *err = nil;
NSArray *arr = [NSJSONSerialization JSONObjectWithData:[str dataUsingEncoding:NSUTF8StringEncoding] options:NSJSONReadingMutableContainers error:&err];

// access the dictionaries
NSMutableDictionary *dict = arr[0];
for (NSMutableDictionary *dictionary in arr) {
  // do something using dictionary
}

4. NSMutableDictionary转换成NSString

未完待续...