1.首先用構(gòu)造方法直接創(chuàng)建

UIActivityIndicatorView *indicatorView = [[UIActivityIndicatorView alloc]init];

此時frame打印結(jié)果{{0, 0}, {0, 0}},并且其屬性hidden = YES
直接添加到視圖上,調(diào)用方法[indicatorView startAnimating];
此時打印frame={{120, 15}, {20, 20}}
也就是,在開啟動畫的時候打印indicatorView.activityIndicatorViewStyle
因為是枚舉值,打印結(jié)果是1,也就是UIActivityIndicatorViewStyleWhite

若是在創(chuàng)建之后,指定indicatorView.activityIndicatorViewStyle,此時打印frame,其值仍為{{0, 0}, {0, 0}},只有在開啟動畫是才能打印出非0值

2.使用initWithActivityIndicatorStyle方法創(chuàng)建,

UIActivityIndicatorView *indicatorView = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];

此時打印frame
UIActivityIndicatorViewStyleWhiteLarge, {{0, 0}, {37, 37}}
UIActivityIndicatorViewStyleWhite, {{0, 0}, {20, 20}}
UIActivityIndicatorViewStyleGray {{0, 0}, {20, 20}}

綜上使用init創(chuàng)建時frame = {{0, 0}, {0, 0}},指定indicatorView.activityIndicatorViewStyle,亦然
使用initWithActivityIndicatorStyle創(chuàng)建,frame根據(jù)activityIndicatorViewStyle確定,且不能更改frame