如何在Objective-C中将PHAsset转换为UIImage [英] How to convert PHAsset to UIImage in Objective-C

问题描述

我有一个充满 PHAsset 对象的数组（ https://developer.apple.com/library/prerelease/ios/documentation/Photos/Reference/PHAsset_Class/index.html ），我想要知道如何将它们转换为UIImage然后将它们保存在数组中。

I have an array filled with PHAsset objects (https://developer.apple.com/library/prerelease/ios/documentation/Photos/Reference/PHAsset_Class/index.html), and I want to know how I can convert them into a UIImage and then save them in an Array.

带有PHAsset对象的数组称为 self.assets ，这是我到目前为止所拥有的：

The array with the PHAsset objects is called self.assets and here is what I have so far:

PHImageManager *manager = [PHImageManager defaultManager];

CGFloat scale = UIScreen.mainScreen.scale;

NSMutableArray *images = [NSMutableArray arrayWithCapacity:[self.assets count]];

for (int i = 0; i < [self.assets count]; i++) {

    CGSize targetSize = CGSizeMake(scale, scale);

    [manager requestImageForAsset:[self.assets objectAtIndex:i]
                       targetSize:targetSize
                      contentMode:PHImageContentModeAspectFill
                          options:self.requestOptions
                    resultHandler:^(UIImage *image, NSDictionary *info){
                        [images addObject:image];
                    }];
}

self.requestOptions是.h

self.requestOptions is a property in the .h

@property (nonatomic, strong) PHImageRequestOptions *requestOptions;

在viewDidLoad中我这样做：

and in the viewDidLoad I am doing this:

self.requestOptions = [[PHImageRequestOptions alloc] init];
self.requestOptions.resizeMode   = PHImageRequestOptionsResizeModeExact;
self.requestOptions.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat;

但经过一些调试后，我一直看到 self.assets 具有以下值：

But after doing some debugging, I keep seeing that self.assets has the following values:

(
<PHAsset: 0x1743828a0> 3B6D658D-EC76-43A1-9793-35D889E9CF15/L0/001 mediaType=1/0, assetSource=3, (2448x2448), creationDate=2015-07-27 02:02:46 +0000, location=1, hidden=0, favorite=0 ,
<PHAsset: 0x174382970> 50F05575-71D2-446B-BD1E-8E3250E375AD/L0/001 mediaType=1/0, assetSource=3, (2448x2448), creationDate=2015-07-27 02:02:47 +0000, location=1, hidden=0, favorite=0 
)

和 images 为空。有谁知道如何添加将PHAssets转换为UIImages并将它们添加到 images 数组？任何帮助表示赞赏。谢谢！

and images is empty. Does anyone know how I can add convert the PHAssets into UIImages and add them to the images array? Any help is appreciated. Thanks!

推荐答案

对于任何在这个问题上挣扎的人来说，这就是你要走的路。

For anyone struggling as much as I had on this issue, this is the way to go.

首先将requestOptions设置为：

First set the requestOptions as:

self.requestOptions = [[PHImageRequestOptions alloc] init];
self.requestOptions.resizeMode   = PHImageRequestOptionsResizeModeExact;
self.requestOptions.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat;

// this one is key
self.requestOptions.synchronous = YES;

如果数组中有多个资产填充了PHAsset对象，则添加以下代码：

and if there are multiple assets in an array filled with PHAsset objects, then add this code:

self.assets = [NSMutableArray arrayWithArray:assets];
PHImageManager *manager = [PHImageManager defaultManager];
NSMutableArray *images = [NSMutableArray arrayWithCapacity:[assets count]];

// assets contains PHAsset objects.
 __block UIImage *ima;

for (PHAsset *asset in self.assets) {
    // Do something with the asset

    [manager requestImageForAsset:asset
                       targetSize:PHImageManagerMaximumSize
                      contentMode:PHImageContentModeDefault
                          options:self.requestOptions
                    resultHandler:^void(UIImage *image, NSDictionary *info) {
                        ima = image;

                        [images addObject:ima];
                    }];


}

现在 images 数组包含 uiimage 格式的所有图像。

and now the images array contains all the images in uiimage format.

这篇关于如何在Objective-C中将PHAsset转换为UIImage的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！