iOS程序开发之使用PlaceholderImageView实现优雅的图片加载效果

//
// PlaceholderImageView.h
// SDWebImageViewPlaceHorder
//
// Created by YouXianMing on 16/9/14.
// Copyright © 2016年 YouXianMing. All rights reserved.
//
#import <UIKit/UIKit.h>
@interface PlaceholderImageView : UIView
/**
* Picture's url string.
*/
@property (nonatomic, strong) NSString *urlString;
/**
* The placeholder's image.
*/
@property (nonatomic, strong) UIImage *placeholderImage;
/**
* Default is UIViewContentModeScaleAspectFill.
*/
@property (nonatomic) UIViewContentMode placeholderImageContentMode;
/**
* Default is UIViewContentModeScaleAspectFill.
*/
@property (nonatomic) UIViewContentMode contentImageContentMode;
@end

//
// ImageCell.h
// SDWebImageViewPlaceHorder
//
// Created by YouXianMing on 16/9/14.
// Copyright © 2016年 YouXianMing. All rights reserved.
//
#import <UIKit/UIKit.h>
#import "PlaceholderImageView.h"
@interface ImageCell : UITableViewCell
@property (nonatomic, strong) PlaceholderImageView *placeholderImageView;
@end
//
// ImageCell.m
// SDWebImageViewPlaceHorder
//
// Created by YouXianMing on 16/9/14.
// Copyright © 2016年 YouXianMing. All rights reserved.
//

@implementation ImageCell
- (instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
if (self = [super initWithStyle:style reuseIdentifier:reuseIdentifier]) {
self.selectionStyle = UITableViewCellSelectionStyleNone;
self.placeholderImageView = [[PlaceholderImageView alloc] initWithFrame:CGRectMake(0, 0, 150.f, 150.f)];
self.placeholderImageView.placeholderImage = [UIImage imageNamed:@"1"];
[self addSubview:self.placeholderImageView];
}
return self;
}
@end

//
// ViewController.m
// SDWebImageViewPlaceHorder
//
// Created by YouXianMing on 16/9/14.
// Copyright © 2016年 YouXianMing. All rights reserved.
//
#import "ViewController.h"
#import "UIImageView+WebCache.h"
#import "PlaceholderImageView.h"
#import "ImageCell.h"
@interface ViewController () <UITableViewDelegate, UITableViewDataSource>
@property (nonatomic, strong) UITableView *tableView;
@property (nonatomic, strong) NSArray *pictures;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.pictures = @[@"https://pic.cnblogs.com/avatar/607542/20151017230728.png",
@"https://pic.cnblogs.com/face/607741/20140226202001.png",
@"https://pic.cnblogs.com/face/815231/20150923160245.png",
@"https://pic.cnblogs.com/face/993558/20160729092113.png",
@"https://pic.cnblogs.com/face/894202/20160217151952.png",
@"https://pic.cnblogs.com/face/968459/20160709111712.png",
@"https://pic.cnblogs.com/face/145865/20160210174306.png",
@"https://pic.cnblogs.com/face/796658/20151026090914.png",
@"https://pic.cnblogs.com/face/933887/20160629214007.png",
@"https://pic.cnblogs.com/face/125303/20130313094252.png",
@"https://pic.cnblogs.com/face/976232/20160730173456.png",
@"https://pic.cnblogs.com/face/969708/20160602120239.png",
@"https://pic.cnblogs.com/face/954541/20160705113740.png",
@"https://pic.cnblogs.com/face/799942/20150818204115.png"];
PlaceholderImageView *pImageView = [[PlaceholderImageView alloc] initWithFrame:CGRectMake(0, 0, 150.f, 150.f)];
[self.view addSubview:pImageView];
pImageView.urlString = @"https://pic.cnblogs.com/avatar/607542/20151017230728.png";
self.tableView = [[UITableView alloc] initWithFrame:self.view.bounds];
self.tableView.delegate = self;
self.tableView.dataSource = self;
self.tableView.rowHeight = 150.f;
[self.view addSubview:self.tableView];
[self.tableView registerClass:[ImageCell class] forCellReuseIdentifier:@"ImageCell"];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return _pictures.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
ImageCell *cell = [tableView dequeueReusableCellWithIdentifier:@"ImageCell"];
cell.placeholderImageView.urlString = _pictures[indexPath.row];
return cell;
}
@end