SDWebimage 在內存方面存在很大的內存問題，靜態的圖片也會出現拉伸問題，動態的gif圖內存峰值更加的高，內存釋放不會及時，
- SDWebImage 對gif的處理主要是在UIImage+GIF這個文件里面，利用ImageIO函數創建二進制數據，如下：
#import "UIImage+GIF.h"
#import <ImageIO/ImageIO.h>
@implementation UIImage (GIF)
+ (UIImage *)sd_animatedGIFWithData:(NSData *)data {
if (!data) {
return nil;
}
//
CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL);
// 取得gif的幀數
size_t count = CGImageSourceGetCount(source);
UIImage *animatedImage;
// 判斷圖片數量如果是1 返回靜態圖片
if (count <= 1) {
animatedImage = [[UIImage alloc] initWithData:data];
}
else {
// 消耗性能的根源 ，在放入數組中播放的時候，核心動畫會在兩幀之間自動生成股間動畫，十分消耗內存，
NSMutableArray *images = [NSMutableArray array];
NSTimeInterval duration = 0.0f;
for (size_t i = 0; i < count; i++) {
CGImageRef image = CGImageSourceCreateImageAtIndex(source, i, NULL);
// 累加時常
duration += [self sd_frameDurationAtIndex:i source:source];
//添加數組
[images addObject:[UIImage imageWithCGImage:image scale:[UIScreen mainScreen].scale orientation:UIImageOrientationUp]];
//釋放image對象
CGImageRelease(image);
}
if (!duration) {
duration = (1.0f / 10.0f) * count;
}
// 設置動圖數組 ，生成動圖
animatedImage = [UIImage animatedImageWithImages:images duration:duration];
}
CFRelease(source);
return animatedImage;
}
由于SDWebImage通過動圖數組來實現動態，造成內存不能及時釋放
解決方法
1 開啟時鐘 ，每次只加載一張圖片，之前的立即釋放 2 使用YYWebimage代替SDWebimage -靜態圖片加載 產生拉伸，如下圖黃色表示拉伸，
#import "ViewController.h"
#import "YYWebImage.h"
static NSString *KDGroundLxrCellID = @"KDGroundLxrCellID";
@interface ViewController ()<UITableViewDelegate,UITableViewDataSource>
@property(strong, nonatomic) UITableView * mainTable;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self CreatMainTable];
}
/**
* 創建maintable
*/
#pragma mark-
#pragma mark- 創建tableview
-(void)CreatMainTable
{
self.mainTable = [[UITableView alloc] initWithFrame:[UIScreen mainScreen].bounds style:UITableViewStyleGrouped];
self.mainTable.delegate = self ;
self.mainTable.dataSource = self ;
self.mainTable.separatorStyle = UITableViewCellSeparatorStyleNone ;
[self.mainTable registerClass:[UITableViewCell class] forCellReuseIdentifier:KDGroundLxrCellID];
//[self.mainTable registerClass:<#(nullable Class)#> forCellReuseIdentifier:<#(nonnull NSString *)#>]
[self.view addSubview:self.mainTable];
}
/**
* mainTable 代理方法實現
*/
-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 100;
}
-(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell =[tableView dequeueReusableCellWithIdentifier:KDGroundLxrCellID];
NSString * str =@"https://d13yacurqjgara.cloudfront.net/users/288987/screenshots/1913272/depressed-slurp-cycle.gif";
NSURL *url =[NSURL URLWithString:str];
UIImage *image =[UIImage imageNamed:@"icon-120.png"];
// [cell.imageView yy_setImageWithURL:url placeholder:image];
[cell.imageView sd_setImageWithURL:url placeholderImage:image];
return cell;
}
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 107.0;
}
-(CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section
{
return 10.0;
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end ```
不懂紅綠色代表的意思參考:http://www.lxweimin.com/p/92d949a6d4e7
* 動態gif效果 注意此時占用內存是110MB ，cpu占用率是0
* 切換YYWebimage對比，內存消耗50MB而cpu占用40%
import "YYWebImageCell.h"
import "YYWebImage.h"
@implementation YYWebImageCell
-(instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
if (self) {
// @property (nonatomic, readonly, strong, nullable) UIImageView *imageView NS_AVAILABLE_IOS(3_0); // default is nil. image view will be created if necessary.
[self setValue:[[YYAnimatedImageView alloc] init] forKey:@"imageView"];
}
return self;
}```
#import "ViewController.h"
#import "YYWebImage.h"
#import "YYWebImageCell.h"
static NSString *KDGroundLxrCellID = @"KDGroundLxrCellID";
@interface ViewController ()<UITableViewDelegate,UITableViewDataSource>
@property(strong, nonatomic) UITableView * mainTable;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self CreatMainTable];
}
/**
* 創建maintable
*/
#pragma mark-
#pragma mark- 創建tableview
-(void)CreatMainTable
{
self.mainTable = [[UITableView alloc] initWithFrame:[UIScreen mainScreen].bounds style:UITableViewStyleGrouped];
self.mainTable.delegate = self ;
self.mainTable.dataSource = self ;
self.mainTable.separatorStyle = UITableViewCellSeparatorStyleNone ;
[self.mainTable registerClass:[YYWebImageCell class] forCellReuseIdentifier:KDGroundLxrCellID];
//[self.mainTable registerClass:<#(nullable Class)#> forCellReuseIdentifier:<#(nonnull NSString *)#>]
[self.view addSubview:self.mainTable];
}
/**
* mainTable 代理方法實現
*/
-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 100;
}
-(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
YYWebImageCell *cell =[tableView dequeueReusableCellWithIdentifier:KDGroundLxrCellID];
NSString * str =@"https://d13yacurqjgara.cloudfront.net/users/288987/screenshots/1913272/depressed-slurp-cycle";
NSURL *url =[NSURL URLWithString:str];
UIImage *image =[UIImage imageNamed:@"icon-120.png"];
[cell.imageView yy_setImageWithURL:url placeholder:image];
return cell;
}
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 107.0;
}
-(CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section
{
return 10.0;
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end```
相比較YYWebimage對內存方面的處理好好過于SDWebImage是犧牲內存來換取流暢度，而對于流暢度SDWebImage缺要好于YYWebimage，各有所長吧