ios 开发之 各种数据类型之间转换 (持续补充)

1.图片转base64串及反转回图片

UIImage图片转成base64字符串：

UIImage *_originImage = [UIImage imageNamed:@"full_playlist_hl.png"];
NSData *_data = UIImageJPEGRepresentation(_image, 1.0f);
3 NSString *_encodedImageStr = [_data base64Encoding];
4 NSLog(@"===Encoded image:
%@", _encodedImageStr);

Base64字符串转UIImage图片：

NSData *_decodedImageData   = [[NSData alloc] initWithBase64Encoding:_encodedImageStr];
UIImage *_decodedImage      = [UIImage imageWithData:_decodedImageData];
NSLog(@"===Decoded image size: %@", NSStringFromCGSize(_decodedImage.size));

2.字符串转nsdate时间

方法一：

          // format: yyyymmddhhmm (24-hour clock)
            NSString *curStr = [dateString substringWithRange:NSMakeRange(0, 4)];

            NSInteger yeardigit = [curStr integerValue];

            curStr = [dateString substringWithRange:NSMakeRange(4, 2)];

            NSInteger monthdigit = [curStr integerValue];

            curStr = [dateString substringWithRange:NSMakeRange(6, 2)];

            NSInteger daydigit = [curStr integerValue];

            curStr = [dateString substringWithRange:NSMakeRange(8, 2)];

            NSInteger hourdigit = [curStr integerValue];

            curStr = [dateString substringWithRange:NSMakeRange(10, 2)];

            NSInteger minutedigit = [curStr integerValue];

            NSDateComponents *dateComps = [[NSDateComponents alloc] init];

            [dateComps setYear:yeardigit];

            [dateComps setMonth:monthdigit];

            [dateComps setDay:daydigit];

            [dateComps setHour:hourdigit];

            [dateComps setMinute:minutedigit];

            NSCalendar *calendar = [NSCalendar currentCalendar];

            NSDate *itemDate = [calendar dateFromComponents:dateComps];

方法二：

根据字符串时间格式

将字符串dateStr转化为nsdate


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

    [dateFormatter setDateFormat:@"y-M-d HH:mm:ss"];

    NSDate *date=[dateFormatter dateFromString:dateStr];


    //这样转化为NSdate 对象


    //如果想转换为：12/2/16 16:49:13代码如下


    //[dateFormatter setDateFormat:@'yy/M/d H:m:s'];


    //NSLog(@'%@',[dateFormatter stringFromDate:date]);


//    NSLog(@"%@",date);

 提取date中时间的年、月、星期、日、时、分和秒

 NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

NSDate *now;

NSDateComponents *comps = [[NSDateComponents alloc] init];

NSInteger unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekdayCalendarUnit |

NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;

 

now=[NSDate date];

comps = [calendar components:unitFlags fromDate:now];

int year=[comps year];

int week = [comps weekday];   

int month = [comps month];

int day = [comps day];

int hour = [comps hour];

int min = [comps minute];

int sec = [comps second];

 

 3.NSString(汉字)和UTF8

参考链接:http://hp-ios.lofter.com/post/244639_8e6599

 

NSString* strA = [@"%E4%B8%AD%E5%9B%BD"stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSString *strB = [@"中国"stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

 4.JSONString转换字典

    /*!  
     * @brief 把格式化的JSON格式的字符串转换成字典  
     * @param jsonString JSON格式的字符串  
     * @return 返回字典  
     */  
    + (NSDictionary *)dictionaryWithJsonString:(NSString *)jsonString {  
        if (jsonString == nil) {  
            return nil;  
        }  
          
        NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];  
        NSError *err;  
        NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:jsonData  
                                                            options:NSJSONReadingMutableContainers  
                                                              error:&err];  
        if(err) {  
            NSLog(@"json解析失败：%@",err);  
            return nil;  
        }  
        return dic;  
    }  

 5.NSData 与 NSString ，Byte数组 ，UIImage的相互转换

//1. NSData 与 NSString
//NSData－> NSString
NSString *aString = [[NSString alloc] initWithData:adata encoding:NSUTF8StringEncoding];

//NSString－>NSData
NSString *aString = @"1234abcd";
NSData *aData = [aString dataUsingEncoding: NSUTF8StringEncoding];

//2.NSData 与 Byte
//NSData－> Byte数组
NSString *testString = @"1234567890";
NSData *testData = [testString dataUsingEncoding: NSUTF8StringEncoding];
Byte *testByte = (Byte *)[testData bytes];
for(int i=0;i<[testData length];i++)
printf("testByte = %d
",testByte[i]);

//Byte数组－> NSData
Byte byte[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23};
NSData *adata = [[NSData alloc] initWithBytes:byte length:24];

//Byte数组－>16进制数
Byte *bytes = (Byte *)[aData bytes];
NSString *hexStr=@"";
for(int i=0;i<[encryData length];i++)
{
NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes[i]&0xff]; ///16进制数
if([newHexStr length]==1)
hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];
else
hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
}
NSLog(@"bytes 的16进制数为:%@",hexStr);

//16进制数－>Byte数组
///// 将16进制数据转化成Byte 数组
NSString *hexString = @"3e435fab9c34891f"; //16进制字符串
int j=0;
Byte bytes[128]; 
 ///3ds key的Byte 数组， 128位
for(int i=0;i<[hexString length];i++)
{
int int_ch;  /// 两位16进制数转化后的10进制数
 
unichar hex_char1 = [hexString characterAtIndex:i]; ////两位16进制数中的第一位(高位*16)
int int_ch1;
if(hex_char1 >= '0' && hex_char1 <='9')
int_ch1 = (hex_char1-48)*16;   //// 0 的Ascll - 48
else if(hex_char1 >= 'A' && hex_char1 <='F')
int_ch1 = (hex_char1-55)*16; //// A 的Ascll - 65
else
int_ch1 = (hex_char1-87)*16; //// a 的Ascll - 97
i++;
 
unichar hex_char2 = [hexString characterAtIndex:i]; ///两位16进制数中的第二位(低位)
int int_ch2;
if(hex_char2 >= '0' && hex_char2 <='9')
int_ch2 = (hex_char2-48); //// 0 的Ascll - 48
else if(hex_char1 >= 'A' && hex_char1 <='F')
int_ch2 = hex_char2-55; //// A 的Ascll - 65
else
int_ch2 = hex_char2-87; //// a 的Ascll - 97
 
int_ch = int_ch1+int_ch2;
NSLog(@"int_ch=%d",int_ch);
bytes[j] = int_ch;  ///将转化后的数放入Byte数组里
j++;
}
NSData *newData = [[NSData alloc] initWithBytes:bytes length:128];
NSLog(@"newData=%@",newData);

//3. 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];

//UIImage－> NSData
NSData *imageData = UIImagePNGRepresentation(aimae);



转载：  http://blog.csdn.net/ganlijianstyle/article/details/7990797