前段时间项目中有一个上传头像的需求,对图片有一些要求: 图片不能超过2M,宽高最大为200 并且相等,支持JPG/GIF/PNG格式图片,本文先写JPG/PNG,后续会再发GIF图片的选取,压缩,上传.
思考的步骤:
- 1 从相册选取图片
- 2 把图片的二进制数据准备好
- 3 封装上传图片的方法
- 4 上传图片
下面详细讲解如何实现每一步:
1 从相册选取图片,我这里是用的原生API,上代码:
//这部分代码是用来打开相册的
UIImagePickerControllerSourceType sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = YES;//是否允许编辑
picker.sourceType = sourceType;
[self presentViewController:picker animated:YES completion:nil];
下面是选取图片后代理方法内的代码:
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
__block UIImage *image = [info objectForKey:@"UIImagePickerControllerEditedImage"];
[self dismissViewControllerAnimated:YES completion:nil];
NSString *assetString = [[info objectForKey:UIImagePickerControllerReferenceURL] absoluteString];
__block NSData *data = [NSData data];
if([assetString hasSuffix:@"GIF"]){
//这个图片是GIF图,这一部分后续文章会出怎么处理
} else {
//准备图片的二进制数据
//上传图片
}
}
2 准备图片的二进制数据:
根据要求对图片的处理分为两步,第一步压缩体积,减小尺寸,第二步转化成二进制数据
2.1 对PNG和JPEG格式图片的处理
2.1.1 对图片进行压缩
我的做法是利用�图形上下文减小尺寸,利用UIImageJPEGRepresentation()压缩体积,上代码(我做了一个分类,方便调用):
UIImage+ZipSizeAndLength.h
#import <UIKit/UIKit.h>
@interface UIImage (ZipSizeAndLength)
- (UIImage *)compressToByte:(NSUInteger)maxLength;
//直接调用这个方法进行压缩体积,减小大小
- (UIImage *)zip;
@end
UIImage+ZipSizeAndLength.m
@implementation UIImage (ZipSizeAndLength)
- (UIImage *)compressToByte:(NSUInteger)maxLength {
// Compress by quality
CGFloat compression = 1;
NSData *data = UIImageJPEGRepresentation(self, compression);
if (data.length < maxLength) return self;
CGFloat max = 1;
CGFloat min = 0;
for (int i = 0; i < 6; ++i) {
compression = (max + min) / 2;
data = UIImageJPEGRepresentation(self, compression);
if (data.length < maxLength * 0.9) {
min = compression;
} else if (data.length > maxLength) {
max = compression;
} else {
break;
}
}
UIImage *resultImage = [UIImage imageWithData:data];
if (data.length < maxLength) return resultImage;
// Compress by size
NSUInteger lastDataLength = 0;
while (data.length > maxLength && data.length != lastDataLength) {
lastDataLength = data.length;
CGSize size = CGSizeMake(200, 200);
UIGraphicsBeginImageContext(size);
[resultImage drawInRect:CGRectMake(0, 0, size.width, size.height)];
resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
data = UIImageJPEGRepresentation(resultImage, compression);
}
resultImage = [UIImage imageWithData:data];
return resultImage;
}
- (UIImage *)zipSize{
if (self.size.width < 200) {
return self;
}
CGSize size = CGSizeMake(200, 200);
UIGraphicsBeginImageContext(size);
[self drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
- (UIImage *)zip{
UIImage *image = [self compressToByte:2*1024*1024];
return [image zipSize];
}
2.1.2 图片压缩完成之后,需要转成二进制数据,对于PNG和JPEG格式的图片转二进制数据很简单,苹果提供了非常简单实用的API:
// return image as PNG. May return nil if image has no CGImageRef or invalid bitmap format
UIKIT_EXTERN NSData * __nullable UIImagePNGRepresentation(UIImage * __nonnull image);
// return image as JPEG. May return nil if image has no CGImageRef or invalid bitmap format. compression is 0(most)..1(least)
UIKIT_EXTERN NSData * __nullable UIImageJPEGRepresentation(UIImage * __nonnull image, CGFloat compressionQuality);
所以,上文中的准备图片的二进制数据,代码为:
//准备图片的二进制数据
image = [image zip];
data = UIImagePNGRepresentation(image);
//上传图片
3 上传文件的方法:
我用AFN做的上传,代码如下:
+(void)requestUrl:(NSString*)urlString paras:(id)paras datas:(NSArray *)datas
success:(SuccessBlock)successBlock failure:(FailureBlock)failureBlock{
NSURLSessionDataTask *datatask = [sessionManager POST:urlString
parameters:paras
constructingBodyWithBlock:^(id<AFMultipartFormData> _Nonnull formData) {
for (int i = 0 ; i < datas.count ; i++){
NSData *data = datas[i];
[formData appendPartWithFileData:data name:@"facefile" fileName:@"facefile" mimeType:@"image/gif"];
}
} progress:^(NSProgress * _Nonnull uploadProgress) {
NSLog(@"-----%@",uploadProgress);
} success:^(NSURLSessionDataTask * _Nonnull task, id _Nullable responseObject) {
NSLog(@"上传成功--%@",responseObject);
} failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
NSLog(@"上传失败%@",error);
}];
}
这里需要注意的一点是: 数据流的name和faileName mimeType 不能为空; 并且name是跟后台约定好的.
所以上文中的上传图片部分的代码为:
//上传图片
[self uploadImageWithData:data];
uploadImageWithData方法实现为:
- (void)uploadImageWithData:(NSData *)data{
NSMutableDictionary *dic = [[NSMutableDictionary alloc]init];
[dic setValue:@"xx" forKey:@"xxx"];
[dic setValue:@"xx" forKey:@"yyy"];
[dic setValue:@"xx" forKey:@"zzz"];
NSString str = @"http://xx.xx.com";
requestUrl:(NSString)urlString paras:(id)paras datas:(NSArray *)datas
[Request requestUrl:str paras:dic datas:@[data] success:^(id responds) {
//成功回调
} failure:^(NSError *error) {
//失败回调
}];
}
