圖片存儲與轉換處理

UIImage圖片存儲以及各種轉換

概述

圖片操作是我們開發中必然會用到的一塊內容，圖片的各種轉換（NSData、Base64String、UIColor等轉換），本地存儲、相冊保存等。

這裏簡單的創建了一個分類(UIImage (MMAddition))來總結了部分圖片相關的存儲於轉換相關的內容。

文件代碼UIImage+MMAddition.{h,m}下載直接使用

下面也是全部代碼的介紹

API

1、 UIImage圖片存儲到沙盒Documents文件夾下面

+ (void) saveImage:(UIImage *)currentImage withName:(NSString *)imageName
{
    NSData *imageData = UIImageJPEGRepresentation(currentImage, 0.5);
    //獲取沙盒Documents路徑
    NSString *DocumentsPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];

    //定義圖片存儲路徑
    NSString *imageFullPath = [DocumentsPath stringByAppendingPathComponent:imageName];

    //將圖片數據寫入文件
    [imageData writeToFile:imageFullPath atomically:NO];
}

2、 UIImage圖片轉換爲Base64String

+ (NSString *)base64StringFromImage:(UIImage *)image {
    NSData *imageData = UIImageJPEGRepresentation(image, 0.5);

    return [UIImage base64forData:imageData];
}

+ (NSString*)base64forData:(NSData*)theData {

    const uint8_t* input = (const uint8_t*)[theData bytes];
    NSInteger length = [theData length];

    static char table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

    NSMutableData* data = [NSMutableData dataWithLength:((length + 2) / 3) * 4];
    uint8_t* output = (uint8_t*)data.mutableBytes;

    NSInteger i,i2;
    for (i=0; i < length; i += 3) {
        NSInteger value = 0;
        for (i2=0; i2<3; i2++) {
            value <<= 8;
            if (i+i2 < length) {
                value |= (0xFF & input[i+i2]);
            }
        }

        NSInteger theIndex = (i / 3) * 4;
        output[theIndex + 0] =                    table[(value >> 18) & 0x3F];
        output[theIndex + 1] =                    table[(value >> 12) & 0x3F];
        output[theIndex + 2] = (i + 1) < length ? table[(value >> 6)  & 0x3F] : '=';
        output[theIndex + 3] = (i + 2) < length ? table[(value >> 0)  & 0x3F] : '=';
    }

    return [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
}

3、 從Base64String生成圖片

+ (UIImage *)imageWithBase64String:(NSString *)base64Str
{
    NSString *str = [NSString string];
    if ([base64Str hasPrefix:@"data:image/jpg;base64,"]) {
        str = base64Str;
    }else{
        str = [NSString stringWithFormat:@"%@%@", @"data:image/jpg;base64,", base64Str];
    }

    NSURL *url = [NSURL URLWithString:str];
    NSData *imageData = [NSData dataWithContentsOfURL:url];

    return [UIImage imageWithImgData:imageData];
}

+ (UIImage *)imageWithImgData:(NSData *)imgData
{
    return [UIImage imageWithData:imgData scale:[UIScreen mainScreen].scale];
}

4、用UIColor生成一張純色圖片

+ (UIImage *)imageWithColor:(UIColor *)color size:(CGSize)size
{
    CGRect rect = CGRectMake(0, 0, size.width, size.height);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}