nsdata使用指南

1. NSData 与 NSString

NSData－> NSString

NSString *aString = [[NSString alloc] initWithData:adata encoding:NSUTF8StringEncoding];

NSString－>NSData

NSString *aString = @"1234abcd";

NSData *aData = [aString dataUsingEncoding: NSUTF8StringEncoding];

//将data类型的数据,转成UTF8的数据

+(NSString *)dataToUTF8String:(NSData *)data

{

NSString *buf = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

return [buf autorelease];

}

//将string转换为指定编码

+(NSString *)changeDataToEncodinString:(NSData *)data encodin:(NSStringEncoding )encodin{

NSString *buf = [[[NSString alloc] initWithData:data encoding:encodin] autorelease];

return buf;

}

2. NSData 与 UIImage

NSData－>UIImage

UIImage *aimage = [UIImage imageWithData: imageData];

//例：从本地文件沙盒中取图片并转换为NSData

NSString *path = [[NSBundle mainBundle] bundlePath];

NSString *name = [NSString stringWithFormat:@"ceshi.png"];

NSString *finalPath = [path stringByAppendingPathComponent:name];

NSData *imageData = [NSData dataWithContentsOfFile: finalPath];

UIImage *aimage = [UIImage imageWithData: imageData];

3.NSData与NSArray NSDictionary

+(NSString *)getLocalFilePath:(NSString *) fileName

{

return [NSString stringWithFormat:@"%@/%@%@", NSHomeDirectory(),@“Documents”,fileName];

}

包括将NSData写进Documents目录

从Documents目录读取数据

在进行网络数据通信的时候，经常会遇到NSData类型的数据。在该数据是dictionary结构的情况下，系统没有提供现成的转换成NSDictionary的方法，为此可以通过Category对NSDictionary进行扩展，以支持从NSData到NSDictionary的转换。声明和实现如下：

+ (NSDictionary *)dictionaryWithContentsOfData:(NSData *)data {

CFPropertyListRef list = CFPropertyListCreateFromXMLData(kCFAllocatorDefault, (CFDataRef)data, kCFPropertyListImmutable, NULL);

if(list == nil) return nil;

if ([(id)list isKindOfClass:[NSDictionary class]]) {

return [(NSDictionary *)list autorelease];

}

else {

CFRelease(list);

return nil;

}

}

NSDate

//函数作用 :date根据formatter转换成string

+(NSString*)dateToString:(NSString *)formatter date:(NSDate *)date

{

NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];

[dateFormatter setDateFormat:formatter];

return[dateFormatter stringFromDate:date];

}

//函数作用 :string类型的时间戳转换成时间

+(NSString*)dateStringToString:(NSString *)dateStr

{

if ([dateStr isKindOfClass:[NSNull class]]) {

return nil;

}

else{

NSInteger time = [dateStr intValue];

NSDate *date = [NSDate dateWithTimeIntervalSince1970:time];

NSString *timestr = [NSString stringWithFormat:@"%@",date];

NSRange rang;

rang.location = 0;

rang.length = 10;

NSString *needtime = [timestr substringWithRange:rang];

return needtime;

}

}

//函数作用 :将日期从原格式转换成需要的格式

+(NSString*)convertDateFormatter:(NSString*)sourceFormatter

targetFormatter:(NSString*)targetFormatter

dateString:(NSString*)dateString

{

NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];

[dateFormatter setDateFormat:sourceFormatter];

NSDate *date = [dateFormatter dateFromString:dateString];

[dateFormatter setDateFormat:targetFormatter];

return[dateFormatter stringFromDate:date];

}

//函数作用 :将日期字符串转换成date

+(NSDate *)stringToDate:(NSString *)formatter dateString:(NSString *)dateString{

NSDateFormatter *dateFormatter= [[[NSDateFormatter alloc] init] autorelease];

[dateFormatter setDateFormat:formatter];

return [dateFormatter dateFromString:dateString];

}

//时间戳转换成时间

NSInteger time = [[dic objectForKey:@"press_date"] intValue];

NSDate *date = [NSDate dateWithTimeIntervalSince1970:time];

NSString *timestr = [NSString stringWithFormat:@"%@",date];

NSRange rang;

rang.location = 0;

rang.length = 10;

NSString *needtime = [timestr substringWithRange:rang];