Xcode加载图片

例如：[UIImage imageName:@“home”]; 加载png 图片

home.png

home@2x.png

home-568h@2x.png

 ========================================

一、非retina 屏幕 (都是3.5 inch ,分辨率:320 * 480)   //1/3G/3GS

     会自动加载home.png

 

二、retina 屏幕

1、3.5 inch (640 * 960)      //  iPhone4/iPhone4S

     会自动加载home@2x.png

 

2、4.0 inch (640 * 1136)    //  iPhone5/iPhone5S/iPhone5C

(1) home-568h@2x.png(如果home 是程序的启动图片,才自动加载)

(2) 如果是retina屏幕,并且不是程序的启动图片,则会自动加载home@2x.png

 

===================================================

一、 home如果是启动图片

iPhone  1/3G/3GS , 3.5 inch, 非retina屏幕, 自动加载 home.png

iPhone  4/4S , 3.5 inch, retina屏幕, 自动加载 home@2x.png

iPhone 5/5S/5C , 4.0inch , retina屏幕, 自动加载 home-568@2x.png

 

二、 home如果不是启动图片

iPhone  1/3G/3GS , 3.5 inch, 非retina屏幕, 自动加载 home.png

iPhone  4/4S , 3.5 inch, retina屏幕, 自动加载 home@2x.png

iPhone 5/5S/5C , 4.0inch , retina屏幕, 自动加载 home@2x.png

 

****************************** 总结 ****************************

home.png :3.5 inch + 非retina 屏幕

home@2x.png :retina屏幕

home-568@2x.png :4.0 inch +retina屏幕 + home是程序的启动图片

 

 

static Singleton *_instance;

+ (instancetype)allocWithZone:(struct _NSZone *)zone{
    
    @synchronized (self) {
        if (!_instance) {
            _instance = [super allocWithZone:zone];
        }
    }
    return _instance;
}

+ (instancetype)shareTools{
    
    @synchronized (self) {
        if (!_instance) {
            _instance = [[self alloc] init];
        }
    }
    
//    static dispatch_once_t onceToken;
//    dispatch_once(&onceToken, ^{
//        _instance = [[self alloc] init];
//    });
    return _instance;
}

- (instancetype)copyWithZone:(NSZone *)zone{

    return _instance;
}

- (instancetype)mutableCopyWithZone:(NSZone *)zone{

    return _instance;
}

 

 

 

static Singleton *_instance;
+ (instancetype)allocWithZone:(struct _NSZone *)zone{
    static dispatch_once_t onceToken;
    
    dispatch_once(&onceToken, ^{
        _instance = [super allocWithZone:zone];
    });

    return _instance;
}


+ (instancetype)shareTools{

    return [[self alloc] init];
}

- (id)copyWithZone:(NSZone *)zone{

    return _instance;
}

- (id)mutableCopyWithZone:(NSZone *)zone{

    return _instance;
}