判断服务器返回的URL是不是gif

1.第一种方法，根据url的后缀

NSString * path = photo.resUrl;

NSString *extensionName = path.pathExtension;

if ([extensionName.lowercaseString isEqualToString:@"gif"]) {

imageType = @"image/gif";

}else{

imageType = @"no";

}

第二种，取出图片数据的第一个字节，根据字节判断，必须说明url必须是可以正常网络请求的url

NSData * data = [NSData dataWithContentsOfURL:[NSURL URLWithString:photo.resUrl]];

uint8_t c;

[data getBytes:&c length:1];

NSString * imageType = nil;

switch (c) {

case 0xFF:

imageType = @"image/jpeg";

case 0x89:

imageType = @"image/png";

case 0x47:

imageType = @"image/gif";

case 0x49:

case 0x4D:

imageType = @"image/tiff";

case 0x52:

default:

break;

}