//獲取沙盒路徑，
 NSString *path_sandox = NSHomeDirectory();
 //創(chuàng)建一個存儲plist文件的路徑
 NSString *newPath = [path_sandox stringByAppendingPathComponent:@/Documents/pic.plist];
 NSMutableArray *arr = [[NSMutableArray alloc] init];
 UIImage *image = [UIImage imageNamed:@"1.png"];
  
 /*
  把圖片轉換為Base64的字符串 

  在iphone上有兩種讀取圖片數(shù)據(jù)的簡單方法: UIImageJPEGRepresentation和UIImagePNGRepresentation. 
  
  UIImageJPEGRepresentation函數(shù)需要兩個參數(shù):圖片的引用和壓縮系數(shù).而UIImagePNGRepresentation只需要圖片引用作為參數(shù).通過在實際使用過程中,
  比較發(fā)現(xiàn): UIImagePNGRepresentation(UIImage* image) 要比UIImageJPEGRepresentation(UIImage* image, 1.0) 返回的圖片數(shù)據(jù)量大很多.
  譬如,同樣是讀取攝像頭拍攝的同樣景色的照片, UIImagePNGRepresentation()返回的數(shù)據(jù)量大小為199K ,
  而 UIImageJPEGRepresentation(UIImage* image, 1.0)返回的數(shù)據(jù)量大小只為140KB,比前者少了50多KB.
  如果對圖片的清晰度要求不高,還可以通過設置 UIImageJPEGRepresentation函數(shù)的第二個參數(shù),大幅度降低圖片數(shù)據(jù)量.譬如,剛才拍攝的圖片, 
  通過調用UIImageJPEGRepresentation(UIImage* image, 1.0)讀取數(shù)據(jù)時,返回的數(shù)據(jù)大小為140KB,但更改壓縮系數(shù)后,
  通過調用UIImageJPEGRepresentation(UIImage* image, 0.5)讀取數(shù)據(jù)時,返回的數(shù)據(jù)大小只有11KB多,大大壓縮了圖片的數(shù)據(jù)量 ,
  而且從視角角度看,圖片的質量并沒有明顯的降低.因此,在讀取圖片數(shù)據(jù)內容時,建議優(yōu)先使用UIImageJPEGRepresentation,
  并可根據(jù)自己的實際使用場景,設置壓縮系數(shù),進一步降低圖片數(shù)據(jù)量大小.
  */
 NSData *_data = UIImageJPEGRepresentation(image, 1.0f);
 //將圖片的data轉化為字符串
 NSString *strimage64 = [_data base64EncodedString];
 
 [arr addObject:image64]; 
  //寫入plist文件 
 if ([arr writeToFile:newPath atomically:YES]) {  
 NSLog(@"寫入成功"); 
 };
  //可以到沙河路徑下查看plist文件中的圖片數(shù)據(jù) 
 //這樣就存起來的，然后用到的時候再利用存儲的字符串轉化為圖片
 //NSData *_decodedImageData = [[NSData alloc] initWithBase64Encoding:image64]; 這是iOS7之前的一個方法 
 
 NSData *_decodedImageData = [[NSData alloc]initWithBase64EncodedString:strimage64 options:NSDataBase64DecodingIgnoreUnknownCharacters];
 UIImage *_decodedImage = [UIImage imageWithData:_decodedImageData];
 
 //可以打印下圖片是否存在
 NSLog(@"===Decoded image size: %@", NSStringFromCGSize(_decodedImage.size));

 //拿到圖片
 UIImage *image2 = [UIImage imageNamed:@"1.png"]; 
 NSString *path_document = NSHomeDirectory();
 //設置一個圖片的存儲路徑
 NSString *imagePath = [path_document stringByAppendingString:@"/Documents/pic.png"];
 //把圖片直接保存到指定的路徑（同時應該把圖片的路徑imagePath存起來，下次就可以直接用來?。?
 [UIImagePNGRepresentation(image2) writeToFile:imagePath atomically:YES];

UIImage *getimage2 = [UIImage imageWithContentsOfFile:imagePath]; 
NSLog(@"image2 is size %@",NSStringFromCGSize(getimage2.size)); 

NSString *homeDirectory = NSHomeDirectory(); 

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
NSString *path = [paths objectAtIndex:0]; 

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES); 
NSString *path = [paths objectAtIndex:0]; 

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES); 
NSString *path = [paths objectAtIndex:0];