ios 加载多张本地图片内存暴增问题解决方法

在使用UICollectionViewCell中加载本地图片会造成界面卡顿，如果只有十几个cell会看不到什么反应，但是如果加载几十上百张的时候就会界面卡顿，这是因为出现了内存暴增的情况，所以现在不能再使用 [UIImage imageNamed:@""]方法了，应该把cell里面的图片进行压缩使用缩略图，这样就会解决界面卡顿，内存也就不会暴增了

cell.m 关键代码

- (void)setModel:(SNZJModel*)model{

    _model= model;

    // 加载本地图片要把图片变成压缩图,否则会内存暴增

    //子线程加载图片

    dispatch_async(dispatch_queue_create(0, 0), ^{

        UIImage*ima = [UIImageimageNamed:model.pic];//存放图片url图集_picUrlArr

        // 压缩图片

        UIImage*newImage = [UIImageimageCompressForSize:imatargetSize:CGSizeMake(KHeight(220) /4, ((SCW-KWidth(30) /3)) /4)];

        // 在主线程加载图片

        dispatch_async(dispatch_get_main_queue(), ^{

            self.papImageView.image= newImage;

        });

    });

}

压缩图片方法

UIImage+SNCompressionImageView.h

#import

NS_ASSUME_NONNULL_BEGIN

@interfaceUIImage(SNCompressionImageView)

+ (UIImage*)imageCompressForSize:(UIImage*)sourceImagetargetSize:(CGSize)size;

@end

NS_ASSUME_NONNULL_END

UIImage+SNCompressionImageView.m

#import "UIImage+SNCompressionImageView.h"

@implementationUIImage(SNCompressionImageView)

+ (UIImage*)imageCompressForSize:(UIImage*)sourceImagetargetSize:(CGSize)size{

    UIImage*newImage =nil;

    CGSizeimageSize = sourceImage.size;

    CGFloatwidth = imageSize.width;

    CGFloatheight = imageSize.height;

    CGFloattargetWidth = size.width;

    CGFloattargetHeight = size.height;

    CGFloatscaleFactor =0.0;

    CGFloatscaledWidth = targetWidth;

    CGFloatscaledHeight = targetHeight;

    CGPointthumbnailPoint =CGPointMake(0.0,0.0);

    if(CGSizeEqualToSize(imageSize, size) ==NO){

        CGFloatwidthFactor = targetWidth / width;

        CGFloatheightFactor = targetHeight / height;

        if(widthFactor > heightFactor){

            scaleFactor = widthFactor;

        }

        else{

            scaleFactor = heightFactor;

        }

        scaledWidth = width * scaleFactor;

        scaledHeight = height * scaleFactor;

        if(widthFactor > heightFactor){

            thumbnailPoint.y= (targetHeight - scaledHeight) *0.5;

        }elseif(widthFactor < heightFactor){

            thumbnailPoint.x= (targetWidth - scaledWidth) *0.5;

        }

    }

    UIGraphicsBeginImageContextWithOptions(size, NO, 3.0);

    CGRectthumbnailRect =CGRectZero;

    thumbnailRect.origin= thumbnailPoint;

    thumbnailRect.size.width= scaledWidth;

    thumbnailRect.size.height= scaledHeight;

    [sourceImagedrawInRect:thumbnailRect];

    newImage =UIGraphicsGetImageFromCurrentImageContext();

    if(newImage ==nil){

        NSLog(@"scale image fail");

    }

    UIGraphicsEndImageContext();

    returnnewImage;

}

目前这个方法是管用的，有更好的方法欢迎评论交流