摘要：
1.将图片转换为base64字符串，并将其反转为图片UIImage。将图片转换为base64字符串：1UIImage*_originImage=[UIImageimageNamed:@“full_playlist_hl.png”]；2NSData*_ data=UIImageJPEG表示（_image，1.0f）；3NSString*_ encodeImageStr=[_database64Enc
1.图片转base64串及反转回图片
UIImage图片转成base64字符串：
1 UIImage *_originImage = [UIImage imageNamed:@"full_playlist_hl.png"]; 2 NSData *_data = UIImageJPEGRepresentation(_image, 1.0f);
3 NSString *_encodedImageStr = [_data base64Encoding]; 4 NSLog(@"===Encoded image: %@", _encodedImageStr);
Base64字符串转UIImage图片：
1 NSData *_decodedImageData = [[NSData alloc] initWithBase64Encoding:_encodedImageStr]; 2 UIImage *_decodedImage = [UIImage imageWithData:_decodedImageData]; 3 NSLog(@"===Decoded image size: %@", NSStringFromCGSize(_decodedImage.size));
2.字符串转nsdate时间
方法一：
1 // format: yyyymmddhhmm (24-hour clock) 4 NSString *curStr = [dateString substringWithRange:NSMakeRange(0, 4)];
7 NSInteger yeardigit = [curStr integerValue]; 9 10 curStr = [dateString substringWithRange:NSMakeRange(4, 2)]; 12 13 NSInteger monthdigit = [curStr integerValue]; 14 16 curStr = [dateString substringWithRange:NSMakeRange(6, 2)]; 17 19 NSInteger daydigit = [curStr integerValue]; 20 22 curStr = [dateString substringWithRange:NSMakeRange(8, 2)]; 23 25 NSInteger hourdigit = [curStr integerValue]; 27 28 curStr = [dateString substringWithRange:NSMakeRange(10, 2)]; 29 31 NSInteger minutedigit = [curStr integerValue]; 37 NSDateComponents *dateComps = [[NSDateComponents alloc] init]; 38 40 [dateComps setYear:yeardigit]; 41 43 [dateComps setMonth:monthdigit]; 44 46 [dateComps setDay:daydigit]; 47 49 [dateComps setHour:hourdigit]; 50 52 [dateComps setMinute:minutedigit]; 54 55 NSCalendar *calendar = [NSCalendar currentCalendar]; 56 58 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
1 NSString* strA = [@"%E4%B8%AD%E5%9B%BD"stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; 2 NSString *strB = [@"中国"stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
4.JSONString转换字典
1 /*! 2 * @brief 把格式化的JSON格式的字符串转换成字典 3 * @param jsonString JSON格式的字符串 4 * @return 返回字典 5 */ 6 + (NSDictionary *)dictionaryWithJsonString:(NSString *)jsonString { 7 if (jsonString == nil) { 8 return nil; 9 } 10 11 NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding]; 12 NSError *err; 13 NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:jsonData 14 options:NSJSONReadingMutableContainers 15 error:&err]; 16 if(err) { 17 NSLog(@"json解析失败：%@",err); 18 return nil; 19 } 20 return dic; 21 }
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